THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 


PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 
A 


THE 

ANCIENT    LIFE-HISTORY 


OF 


THE    EARTH 


International  Science  library 
THE 

ANCIENT    LIFE-HISTORY 


OF 


THE    EARTH 


A  COMPREHENSIVE   OUTLINE  OF  THE   PRINCIPLES  AND   LEADING 
FACTS    OP    PALAEONTOLOGICAL    SCIENCE 


BY 

H.  'ALLEYNE  NICHOLSON 

M.  D.,  D.  Sc.,  M.A..   PH.D.   (Gorr.),   F.  R.  S.  E.,   F.  L.  S. 

PROFESSOR    OF    NATURAL    HISTORY    IN    THt 
UNIVERSITY    OF    ST.   ANDREWS       • 


Tiderner  Company 

JSooh  flftanutactur.:re 

fc  r  o  n  ,     ©bio 


PALEO, 
L1BR. 

Gift  of  C.  A.  Kofoid 


WERNER    EDITION 


.  a 

£ARTH 
SCIENCES 
11BRABY 


PREFACE. 


THE  study  of  Palaeontology,  or  the  science  which  is 
concerned  with  the  living  beings  which  flourished  upon 
the  globe  during  past  periods  of  its  history,  may  be 
pursued  by  two  parallel  but  essentially  distinct  paths. 
By  the  one  method  of  inquiry,  we  may  study  the  ana- 
tomical characters  and  structure  of  the  innumerable 
extinct  forms  of  life  which  lie  buried  in  the  rocks 
simply  as  so  many  organisms,  with  but  a  slight  and 
secondary  reference  to  the  time  at  which  they  lived. 
By  the  other  method,  fossil  animals  are  regarded  prin- 
cipally as  so  many  landmarks  in  the  ancient  records  of 
the  world,  and  are  studied  historically  and  as  regards 
their  relations  to  the  chronological  succession  of  the 
strata  in  which  they  are  entombed.  In  so  doing,  it  is 
of  course  impossible  to  wholly  ignore  their  structural 
characters,  and  their  relationships  with  animals  now 
living  upon  the  earth ;  but  these  points  are  held  to 
occupy  a  subordinate  place,  and  to  require  nothing 
more  than  a  comparatively  general  attention. 

In  a  former  work,  the  Author  has  endeavored  to 
furnish  a  summary  of  the  more  important  facts  of 
Palaeontology  regarded  in  its  strictly  scientific  aspect, 

(v) 

M332350 


vi  PREFACE. 

as  a  mere  department  of  the  great  science  of  Biology. 
The  present  work,  on  the  other  hand,  is  an  attempt  to 
treat  Palaeontology  more  especially  from  its  historical 
side,  and  in  its  more  intimate  relations  with  Geology. 
In  accordance  with  this  object,  the  introductory  por- 
tion of  the  work  is  devoted  to  a  consideration  of  the 
general  principles  of  Palaeontology,  and  the  bearings 
of  this  science  upon  various  geological  problems — such 
as  the  mode  of  formation  of  the  sedimentary  rocks, 
the  reactions  of  living  beings  upon  the  crust  of  the 
earth,  and  the  sequence  in  time  of  the  fossiliferous  for- 
mations. The  second  portion  of  the  work  deals  exclu- 
sively with  Historical  Palaeontology,  each  formation 
being  considered  separately,  as  regards  its  lithological 
nature  and  subdivisions,  its  relations  to  other  forma- 
tions, its  geographical  distribution,  its  mode  of  origin, 
and  its  characteristic  life-forms. 

In  the  consideration  of  the  characteristic  fossils  of 
each  successive  period,  a  general  account  is  given  of 
their  more  important  zoological  characters  and  their 
relations  to  living  forms ;  but  the  technical  language  of 
Zoology  has  been  avoided,  and  the  aid  of  illustrations 
has  been  freely  called  into  use.  It  may  therefore  be 
hoped  that  the  work  may  be  found  to  be  available  for 
the  purposes  of  both  the  Geological  and  the  Zoological 
student;  since  it  is  essentially  an  outline  of  Historical 
Palaeontology,  and  the  student  of  either  of  the  above- 
mentioned  sciences  must  perforce  possess  some  knowl- 
edge of  the  last.  Whilst  primarily  intended  for  stu- 
dents, it  may  be  added  that  the  method  of  treatment 
adopted  has  been  so  far  untechnical  as  not  to  render 
the  work  useless  to  the  general  reader  who  may  desire 
to  acquire  some  knowledge  of  the  subject  of  such  vast 
and  universal  interest. 

In  carrying  out  the  object  which  he  has  held  before 
him,  the  Author  can  hardly  expect,  from  the  nature  of 


PREFACE.  vii 

the  materials  with  which  he  has  to  deal,  that  he  has 
kept  himself  absolutely  clear  of  errors,  both  of  omis- 
sion and  commission.  The  subject,  however,  is  one  to 
which  he  has  devoted  the  labor  of  many  years,  both 
in  studying  the  researches  of  others  and  in  personal 
investigations  of  his  own  ;  and  he  can  only  trust  that 
such  errors  as  may  exist  will  be  found  to  belong  chiefly 
to  the  former  class,  and  to  be  neither  serious  nor 
numerous.  It  need  only  be  added  that  the  work  is 
necessarily  very  limited  in  its  scope,  and  that  the  ne- 
cessity of  not  assuming  a  thorough  previous  acquaint- 
ance with  Natural  History  in  the  reader  has  inexorably 
restricted  its  range  still  further.  The  Author  does  not, 
therefore,  profess  to  have  given  more  than  a  merely 
general  outline  of  the  subject;  and  those  who  desire  to 
obtain  a  more  minute  and  detailed  knowledge  of 
Palaeontology,  must  have  recourse  to  other  and  more 
elaborate  treatises. 

UNITED  COLLEGE,  ST.  ANDREWS. 
October  2,  1876. 


CONTENTS. 


PART    I. 

PRINCIPLES  OF  PALAEONTOLOGY. 
INTRODUCTION. 

PAGE 

The  general  objects  of  geological  science — The  older  theories 
of  catastrophistic  and  intermittent  action — The  more 
modern  doctrines  of  continuous  and  uniform  action — 
Bearing  of  these  doctrines  respectively  on  the  origin  of 
the  existing  terrestrial  order — Elements  of  truth  in 
Catastrophism— General  truth  of  the  doctrine  of  Con- 
tinuity— Geological  time . . . ." I-IO 

CHAPTER  I. 

Definition  of  Palaeontology — Nature  of  Fossils — Different 
processes  of  f osilization 10-14 

CHAPTER  II. 

Aqueous  and  igneous  rocks — General  characters  of  the 
sedimentary  rocks — Mode  of  formation  of  the  sedi- 
mentary rocks — Definition  of  the  term  "  formation  " — 
Chief  divisions  of  the  aqueous  rocks — Mechanically- 
formed  rocks,  their  characters  and  mode  of  origin — 
Chemically  and  organically  formed  rocks — Calcareous 
rocks — Chalk,  its  microscopic  structure  and  mode  of 
formation — Limestone,  varieties,  structure,  and  origin — 
Phosphate  of  lime — Concretions — Sulphate  of  lime — 
Silica  and  siliceous  deposits  of  various  kinds — Green- 
sands — Red  clays — Carbon  and  carbonaceous  deposits.  .15-38 
(ix) 


x  CONTENTS. 

CHAPTER  III. 

Chronological  succession  of  the  fossiliferous  rocks — Tests 
of  age  of  strata— Value  of  Palaeontological  evidence  in 
stratigraphical  Geology — General  sequence  of  the  great 
formations 38-45 

CHAPTER  IV. 

The  breaks  in  the  palaeontological  and  geological  record — 
Use  of  the  term  "  contemporaneous "  as  applied  to 
groups  of  strata — General  sequence  of  strata  and  of  life- 
forms  interfered  with  by  more  or  less  extensive  gaps — 
Unconformability — Phenomena  implied  by  this — Causes 
of  the  imperfection  of  the  palaeontological  record 45~53 

CHAPTER  V. 

Conclusions  to  be  drawn  from  fossils — Age  of  rocks — Mode 
of  origin  of  any  fossiliferous  bed — Fluviatile,  lacustrine, 
and  marine  deposits — Conclusions  as  to  climate — Proofs 
of  elevation  and  subsidence  of  portions  of  the  earth's 
crust  derived  from  fossils 53-58 

CHAPTER  VI. 

The  biological  relations  of  fossils — Extinction  of  life-forms 
— Geological  range  of  different  species — Persistent  types 
of  life — Modern  origin  of  existing  animals  and  plants — 
Reference  of  fossil  forms  to  the  existing  primary  divi- 
sions of  the  animal  kingdom — Departure  of  the  older 
types  of  life  from  those  now  in  existence — Resemblance 
of  the  fossils  of  a  given  formation  to  those  of  the  for- 
mation next  above  and  next  below — Introduction  of  new 
life-forms 58-62 


PART    II. 
HISTORICAL    PALAEONTOLOGY. 

CHAPTER  VII. 

The  Laurentian  and  Huronian  periods — General  nature, 
divisions,  and  geographical  distribution  of  the  Lauren- 
tian deposits — Lower  and  Upper  Laurentian — Reasons 
for  believing  that  the  Laurentian  rocks  are  not  azoic 
based  upon  their  containing  limestones,  beds  of  oxide 
of  iron,  and  graphite — The  characters,  chemical  com- 
position, and  minute  structure  of  Eozoon  Canadense — 
Comparison  of  Eozoon  with  existing  Foraminifcra — 
Archceosphcerince — Huronian  formation — Nature  and  dis- 
tribution of  Huronian  deposits — Organic  remains  of  the 
Huronian— Literature 65-77 


CONTENTS.  xi 

CHAPTER  VIII. 

The  Cambrian  period — General  succession  of  Cambrian  de- 
posits in  Wales — Lower  Cambrian  and  Upper  Cambrian 
— Cambrian  deposits  of  the  continent  of  Europe  and 
North  America — Life  of  the  Cambrian  period — Fucoids 
— Eophyton — Oldhamia  —  Sponges  —  Echinoderms — An  - 
nelides — Crustaceans — Structure  of  Trilobites — Brachio- 
pods,  Gasteropods,  and  Bivalves — Cephalopods — Litera- 
ture    77-91 

CHAPTER  IX. 

The  Lower  Silurian  period — The  Silurian  rocks  generally — 
Limits  of  Lower  and  Upper  Silurian — General  succession, 
subdivisions,  and  characters  of  the  Lower  Silurian  rocks 
of  Wales — General  succession,  subdivisions  and  charac- 
ters of  the  Lower  Silurian  rocks  of  the  North  American 
continent — Life  of  the  period — Fucoids — Protozoa — 
Graptolites — Structure  of  Graptolites — Corals  —  General 
structure  of  Corals  —  Crinoids  —  Cystideans  —  General 
character  of  Cystideans — Annelides — Crustaceans — Poly- 
zoa — Brachiopods  —  Bivalve  and  Univalve  Molluscs  — 
Chambered  Cephalopods  —  General  characters  of  the 
Cephalopoda — Conodonts 91-116 


CHAPTER  X. 

The  Upper  Silurian  period — General  succession  of  the  Upper 
Silurian  deposits  of  Wales — Upper  Silurian  deposits  of 
North  America — Life  of  the  Upper  Silurian — Plants — 
Protozoa — Graptolites — Corals— Crinoids — General  struc- 
ture of  Crinoids — Star-fishes — Annelides — Crustaceans — 
Eurypterids — Polyzoa — Brachiopods — Structure  of  Bra- 
chiopods— Bivalves  and  Univalves — Pteropods — Cephal- 
opods—Fishes— Silurian  literature 116-134 


CHAPTER  XI. 

The  Devonian  period — Relation  between  the  Old  Red  Sand- 
stone and  the  marine  Devonian  deposits — The  Old  Red 
Sandstone  of  Scotland — The  Devonian  strata  of  Devon- 
shire— Sequence  and  subdivisions  of  the  Devonian  de- 
posits of  North  America — Life  of  the  period — Plants — 
Protozoa — Corals — Crinoids — Pentremites  —  Annelides — 
Crustaceans — Insects  —  Polyzoa  —  Brachiopods — Bivalves 
— Univalves — Pteropods —  Cephalopods — Fishes — General 
divisions  of  the  Fishes — Palaeontological  evidence  as  to 
the  independent  existence  of  the  Devonian  system  as  a 
distinct  formation — Literature 134-160 


xii  CONTENTS. 

CHAPTER  XII. 

The  Carboniferous  period — Relations  of  Carboniferous  rocks 
to  Devonian — The  Carboniferous  Limestone  or  Sub-Car- 
boniferous series — The  Millstone-grit  and  the  Coal- 
measures — Life  of  the  period — Structure  and  mode  of 
formation  of  Coal — Plants  of  the  Coal 160-174 

CHAPTER  XIII. 

Animal  life  of  the  Carboniferous  period — Protozoa — Corals — 
Crinoids  —  Pentremites  —  Structure  of  Pentremites  — 
Echinoids — Structure  of  Echinoidea — Annelides — Crus- 
tacea— Insects — Arachnids  —  Myriapods — Polyzoa  —  Bra- 
chiopods — Bivalves  and  Univalves — Cephalopods — Fishes 
— Labyrinthodont  Amphibians — Literature 174-196 

CHAPTER  XIV. 

The  Permian  period — General  succession,, characters,  and 
mode  of  formation  of  the  Permian  deposits — Life  of  the 
period — Plants — Protozoa — Corals — Echinoderms — Anne- 
lides— Crustaceans — Polyzoa — Brachiopods  —  Bivalves  — 
Univalves — Pteropods  —  Cephalopods  —  Fishes  —  Amphi- 
bians— Reptiles — Literature 196-208 

CHAPTER  XV. 

The  Triassic  period — General  characters  and  subdivisions  of 
the  Trias  of  the  Continent  of  Europe  and  Britain — Trias 
of  North  America — Life  of  the  period — Plants — Echin- 
oderms— Crustaceans — Polyzoa — Brachiopods  —  Bivalves 
— Univalves — Cephalopods — Intermixture  of  Palaeozoic 
with  Mesozoic  types  of  Molluscs — Fishes — Amphibians — 
Reptiles — Supposed  footprints  of  Birds  —  Mammals — 
Literature . . '. 208-232 

CHAPTER  XVI. 

The  Jurassic  period — General  sequence  and  subdivision  of 
the  Jurassic  deposits  in  Britain — Jurassic  rocks  of  North 
America — Life  of  the  period — Plants — Corals — Echino- 
derms— Crustaceans — Insects  —  Brachiopods — Bivalves  — 
Univalves  —  Pteropods  —  Tetrabranchiate  Cephalopods — 
Dibranchiate  Cephalopods  —  Fishes  —  Reptiles  —  Birds — 
Mammals — Literature 232-264 

CHAPTER  XVII. 

The  Cretaceous  period — General  succession  and  subdivisions 
of  the  Cretaceous  rocks  in  Britain — Cretaceous  rocks  of 
North  America — Life  of  the  period — Plants — Protozoa — 
Corals — Echinoderms — Crustaceans — Polyzoa  —  Brachio- 
pods— Bivalves — Univalves — Tetrabranchiate  and  Dibran- 
chiate Cephalopods — Fishes  —  Reptiles  —  Birds  —  Litera- 
ture    264-293 


CONTENTS.  xiii 

CHAPTER  XVIII. 

The  Eocene  period — Relation  between  the  Kainozoic  and 
Mesozoic  rocks  in  Europe  and  in  North  America — Classi- 
fication of  the  Tertiary  deposits — The  sequence  and  sub- 
divisions of  the  Eocene  rocks  of  Britain  and  France — 
Eocene  strata  of  the  United  States — Life  of  the  period — 
Plants — Foraminif  era — Corals — Echinoderms  —  Mollusca 
— Fishes — Reptiles — Birds — Mammals 294-316 

CHAPTER  XIX. 

The  Miocene  period — Miocene  strata  of  Britain — Of  France 
—Of  Belgium— Of  Austria— Of  Switzerland— Of  Ger- 
many— Of  Greece — Of  India — Of  North  America — Of 
the  Arctic  regions — Life  of  the  period — Vegetation  of  the 
Miocene  period — Foraminif  era — Corals  —  Echinoderms — 
Articulates — Mollusca — Fishes — Amphibians  —  Reptiles — 
Mammals 316-334 


CHAPTER  XX. 

The  Pliocene  period — Pliocene  deposits  of  Britain — Of  Eu- 
rope— Of  North  America — Life  of  the  period — Climate 
of  the  period  as  indicated  by  the  Invertebrate  animals — 
The  Pliocene  Mammalia — Literature  relating  to  the 
Tertiary  deposits  and  their  fossils 335-346 

CHAPTER  XXI. 

The  Post-Pliocene  period — Division  of  the  Quaternary  de- 
posits into  Post-Pliocene  and  Recent — Relations  of  the 
Post-Pliocene  deposits  of  the  northern  hemisphere  to  the 
"  Glacial  period  " — Pre-Glacial  deposits — Glacial  deposits 
— Arctic  Mollusca  in  Glacial  beds — Post-Glacial  deposits 
— Nature  and  mode  of  formation  of  high-level  and  low- 
level  gravels — Nature  and  mode  of  formation  of  cavern- 
deposits — Kent's  Cavern — Post-Pliocene  deposits  of  the 
southern  hemisphere 346-357 


CHAPTER  XXII. 

Life  of  the  Post-Pliocene  period — Effect  of  the  coming  on 
and  departure  of  the  Glacial  period  upon  the  animals 
inhabiting  the  northern  hemisphere — Birds  of  the  Post- 
Pliocene — Mammalia  of  the  Post-Pliocene — Climate  of 
the  Post-Glacial  period  as  deduced  from  the  Post-Glacial 
Mammals — Occurrence  of  the  bones  and  implements  of 
Man  in  Post-Pliocene  deposits  in  association  with  the 
remains  of  extinct  Mammalia — Literature  relating  to  the 
Post- Pliocene  period 358-380 


xiv  CONTENTS. 

CHAPTER  XXIII. 

The  succession  of  life  upon  the  globe — Gradual  and  succes- 
sive   introduction    of     life-forms — What    is    meant    by 
"  lower  "  and  "  higher  "  groups  of  animals  and  plants — 
Succession  in  time  of  the  great  groups  of  animals  in  the 
main  corresponding  with  their  zoological  order — Identi- 
cal  phenomena   in    the   vegetable    kingdom — Persistent 
types  of  life — High  organization  of  many  early  forms — 
Bearings  of   Palaeontology  on   the  general   doctrine  of 
Evolution 381-388 

APPENDIX. — Tabular  view  of  the  chief  Divisions  of  the  Ani- 
mal   Kingdom 389-392 

GLOSSARY 393-415 

INDEX 416-430 


LIST  OF   ILLUSTRATIONS. 


FIG. 

1.  Cast  of  Trigonia  longa, 

2.  Microscopic  section  of 

the  wood  of  a  fossil 
Conifer  ............. 

3.  Microscopic  section  of 

the  wood  of  the  Larch 

4.  Section    of    Carbonife- 

rous strata,  Kinghorn, 
Fife  ............... 

5.  Diagram  illustrating  the 

formation  of  strati- 
fied deposits  ......... 

6.  Microscopic  section  of 

a  calcareous  breccia.. 

7.  Microscopic   section   of 

White  Chalk  ........ 

8.  Organisms   in   Atlantic 

Ooze  ............... 

9.  Crinoidal  marble  ...... 

10.  Piece     of     Nummulitic 

limestone,  Pyramids. 

11.  Microscopic  section  of 

Foraminif  eral  _  lime- 
stone —  Carboniferous 
America  ............ 

12.  Microscopic  section  of 

Lower  Silarian  lime- 
stone ............... 

13.  Microscopic  section  of 

oolitic  limestone,  Ju- 
rassic .............. 

14.  Microscopic  section  of 

oolitic  limestone,  car- 
boniferous .......... 

15.  Organisms    in     Barba- 

does   earth  .......... 

16.  Organisms  in  Richmond 

earth  ............... 

17.  Ideal     section     of     the 

crust  of  the  earth... 

18.  Unconformable  June- 

tion  of  Chalk  and  Eo- 
cene rocks  .......... 

19.  Erect  trunk  of  a  Sigil- 

laria    ............... 

20.  Diagrammatic     section 


13 


14 


14 


16 


17 
20 
23 

24 

25 

26 


28 
28 
30 

31 

34 
34 
44 

50 


55 
(xv) 


FIG. 


21. 


22. 


23- 


24. 


27. 

28. 
29. 
30. 
31- 

32. 

33- 
34- 

35- 
36. 

39- 

40. 

41. 
42. 
43- 
44- 
45- 
46. 
47- 


PAGE 

of     the     Laurentian 
rocks 66 

Microscopic  section  of 

Laurentian  limestone    67 
Fragment  of  a  mass  of 

Eozoon   Canadense..     69 
Diagram  illustrating  the 

structure  of  EozoVn.     70 
Microscopic  section  of 

Eozo'dn  Canadense...   71 
Nonionina  and  Gromia    72 
Group  of  shells  of  liv- 
ing Foraminif  era ....     73 
Diagrammatic      section 

of  Cambrian  strata...  78 
Eophyton  Linneanum. .     81 

Oldhamia   antiqua 82 

Scolithus  Canadensis..  83 
Group  of  Cambrian 

Trilobites    85 

Group  of  characteristic 

Cambrian   fossils 88 

Fragment     of    Dictyo- 

nema  sociale 89 

Generalized  section  ^of 
the  Lower  Silurian 

rocks  of  Wales 95 

Generalized  section  of 
the  Lower  Silurian 
rocks  of  North  Ame- 
rica    97 

Licrophycus  Ottawaen- 

sis  98 

Astylospongia  prcemorsa  99 
Stromatopora  rugosa..  loo 
Dichograptus  octobra- 

chiatus IO2 

Didymograptus     diava- 

ricatus   103 

Diplograptus  pristis...  103 
Phyllograptus  typus...  103 

Zaphrentis   Stokesi 105 

Strombodes  pentagonus  105 
Columnaria    alveolata..   106 
Group  of  Cystideans..  107 
Group  of  Lower  Silu- 
rian   Crustaceans...    108 


XVI 


LIST  OF  ILLUSTRATIONS. 


48.  Ptilodictya    falciformis  109 

49.  Ptilodictya  S  chaff  eri. .    109 

50.  Group  of  Lower   Silu- 

rian Brachiopods. . . .   no 

51.  Group  of  Lower   Silu- 

rian    Brachiopods...   in 

52.  Murchisonia   gracilis...   112 

53.  Bellerophon   argo 113 

54.  Maclurea    crenulata...    113 

55.  Orthoceras      crebrisep- 

tum  114 

56.  Restoration    of    Ortho- 

ceras     114 

57.  Generalized   section   of 

the     Upper     Silurian 
rocks    119 

58.  Monograptus  priodon..   121 

59.  Halysites      catenularia 

and  H.   agglomerata   122 

60.  Group   of  Upper  Silu- 

rian   Star-fishes 123 

61.  Protaster  Sedgwickii..   123 

62.  Group   of   Upper   Silu- 

rian Crinoids 124 

63.  Planolites  vulgaris....    125 

64.  Group   of   Upper   Silu- 

rian   Trilobites 126 

65.  Pterygotus   Anglicus...   127 

66.  Group  of  Upper   Silu- 

rian Polyzoa 128 

67.  Spirifera   hyst erica 128 

68.  Group   of  Upper   Silu- 

rian Brachiopods 129 

69.  Group  of  Upper   Silu- 

rian Brachiopods....   129 

70.  Pentamerus   Knightii. .   130 

71.  Cardiola  interrupta,  C. 

fibrosa,  and  Pterinaa 
subfalcata   130 

72.  Group   of  Upper   Silu- 

rian Univalves 131 

73.  Tentaculites   ornatus...   131 

74.  Pteraspis  Banksii 132 

75.  Onchus        tenuistriatus 

and  Thelodus 132 

76.  Generalized   section   of 

the    Devonian    rocks 

of  North  America. . .   139 

77.  Psilophyton    prince ps. .    140 

78.  Prototaxites  Logani. . .    141 

79.  Stromatopora    tubercu- 

lata    142 


80.  Cystiphyllum  vesiculo- 

sum  ................   143 

81.  Zaphrentis   cornicula.    143 

82.  Heliophyllum  exiguum  143 

83.  Crepidophyllum  Archi- 

aci.  .  .  .  .............     144 

84.  Favorsites  Gothlandica  145 

85.  Favo  sites    hemisph&r- 

ica  ..................   145 

86.  Spirorbis    omphalodes 

and  S.  Arkonensis.  .  .  146 
Spirorbis  laxus  and  s. 

spinulifera  ..........    146 

Group  of  Devonian 

Trilobites 


87. 
88. 
89.  Wing  of  Platephem- 


147 


147. 


era  antiqua  .......... 

90.  Clathropora  intertexta  148 

91.  Ceriopora     Hamilton- 

ensis  ................    148 

92.  Fenestella  magnifica..   148 

93.  Retepora  Phillip  si  ____   148 

94.  Fenestella    cribrosa...   148 

95.  Spirifera    sculptilis  .  .  .   149 

96.  Spirifera     mucronata     149 

97.  Atrypa    reticularis.  ...    150 

98.  Strophomena       rhom- 

boidalis  .............    150 

99.  Platyceras    dumosium    151 

100.  Conularia   ornata  .....    151 

101.  Clymenia   Sedwickii.  .    152 

102.  Group  of  Fishes  from 

the    Devonian    rocks 

of   North   America..   154 

103.  Cephalaspis  Lyellii.  .  .    155 

104.  Pterichthys    cornutus    156 

105.  Polypterus  and  Osteo- 

lepis  ................    157 

1  06.  Holoptychius     nobilis- 

simus.  ..............    158 

107.  Generalized  section  of 
'  the        Carboniferous 

rocks    of    the    North 

of    England  .........   164 

108.  Odontopteris   Schloth- 

eimii  ...............     168 

109.  Catamites      cannafor- 

mis  .................    169 

no.  Lepidodendron  Stern- 

bergii  ...............    171 

1  1  r.  Sigillaria    Gr&seri  .....  172 

112.  Stigmaria  ficoides  ----  173 


LIST  OF  ILLUSTRATIONS. 


113.  Trigonocarpum     Ova- 

turn 173 

114.  Microscopic  section  of 

Foraminiferal  lime- 
stone— Carboniferous, 
North  America 175 

115.  Fusulina  cylindrica. . .    176 

116.  Group  of  Carbonifer- 

ous Corals 178 

117.  Platycrinus      triconta- 

dactylus 179 

118.  Pentremites      pyrifor- 

mis  and  P.  conoideus  180 

119.  Archceocidaris    ellipti- 

cus 181 

120.  Spirorbis       Carbonar- 

ms 182 

121.  Prestwichia       rotund- 

data t 183 

122.  Group  of   Carbonifer- 

ous Crustaceans 184 

123.  Cyclophthalmus  senior  185 

124.  Xylobius    sigillarice. . .    186 

125.  Haplophlebium    Barn- 

esi 186 

126.  Group  of  Carbonifer- 

ous   Polyzoa 187 

127.  Group  of   Carbonifer- 

ous   Brachiopoda. . . .    189 

128.  Pupa    vetusta 190 

129.  Goniatites   Fosse? 191 

130.  Amblypterus    macrop- 

terus 192 

131.  Cochliodus  contortus.    193 

132.  Anthracosaurus     Rus- 

selli 194 

!33-  Generalized  section  of 

the  Permian  rocks..    199 

134.  Walchia  piniformis. . .  200 

135.  Group      of      Permian 

Brachiopods 202 

136.  Area     antiqua 203 

137.  Platysomus    gibbosus    203 

138.  Protorosaurus  Speneri  205 

139.  Generalized  section  of 

the  Triassic  rocks...  211 

140.  Zamia  spiralis 213 

141. Triassic    Conifers    and 

Cycads 214 

142.  Enerinus  liliiformis. . .  215 

143.  Aspidura  toricata 215 

144.  Group  of  Triassic  Bi- 

valves  2j6 

145.  Ceratites    nodosus 218 


146. 

147. 
148. 

149. 
150. 
151. 
152. 

153. 
154. 

155. 

156. 
157. 
158. 
159. 
160. 

161. 
162. 

163. 

164. 
165. 

166. 
167. 
168. 
169. 
170. 

171. 
172. 
173. 


174. 
175. 
176. 


Tooth     of     Ceratodus 

seratus  and  C.  altus  220 
Ceratodus  Fosteri....  221 
Footprints  of  Cheiro- 

therium  .............   222 

Section    of    tooth    of 

Labyrinthodont  ......    223 

Skull     of     Mastodon- 

saurus  ..............    223 

Skull  of  Rhynchosau- 

rus  .................    224 

Belodon,  Nothosaurus, 

Palceosaurus,  etc.,  .  .  .   225 
Placodus  gigas  .......  226 

Skulls    of    Dicynodon 

and  Oudenodon.  .  .  .  227 
Supposed  footprint  of 

Bird,  from  the  Trias 

of  Connecticut  ......   228 

Lower  jaw  of  Droma- 

therium  syhestre  ----  229 
Molar  tooth  of  Micro- 

lestes  antiquus  ......   229 

'Myrmecobius       fasci- 

atus  ................    230 

Generalized  section  of 

the  Juriassic  rocks..  236 
Mantellia      megaloph- 
lla  .................   237 

238 


Thecosmilia  annularis 
Pentacrinus  fasciculo- 

sus  .................    239 

Hemicidaris    crenula- 

ris  .................     240 

Eryon  arctiformis  ----   241 

Group      of      Jurassic 

Brachiopods  ......  .  .     242 

Ostrea    Marshii.  ......  .243 

Gryphcea  incurva  .....   243 

Diceras  arietina  ......  243 

Nerincea  Goodhallii...  244 
Ammonites  Humph- 

resianus  ............    245 

Ammonites  bifrons...  245 
Beloteuthis  subcostata  247 
Belemnite  restored; 

diagram    of     Belem- 

nite ;  Belemnites  can- 

aliculata  ............    248 

Tetragonolepsis  ......    248 

Aerodus   nobilis  ......  249 

Ichthyosaurus       com- 

munis  ...............    249 


LIST  OF  ILLUSTRATIONS. 


177.  Plesiosaurus    dolicho- 

deirus 251 

178.  Pterodactylus   crassir- 

ostris 253 

179    Ramphorhynchus 

Bucklandi,    restored    255 

180.  Skull  of  Megalosaurus  256 

181.  Archaopteryx       mac- 

rura 259 

182.  Archceopteryx,   restor- 

ed      259 

183.  Jaw     of     Amphither- 

ium    Prevostii 261 

184.  Jaws  of  Oolitic  Mam- 

mals    261 

185.  Generalized  section  of 

the  Cretaceous  rocks  268 

186.  Cretaceous        Angios- 

perms 271 

187    Rotalia    Boueana 272 

188.  Siphonia   ficus 273 

189.  Ventriculites   simplex   273 

190.  Synhelia    Sharpeana. .  274 

191.  Galerites    albogalerus    275 

192.  Discoidea   cylindrica. .  275 

193.  Escharina    Oceani....  276 

194.  TerebratellaAstieriana  276 

195.  Crania    Ignabergenis    277 

196.  Ostrea    Coulom 277 

197.  Spondylus    spinosus..   278 

198.  Inoceramus    sulcatus    278 

199.  Hippurites       Toucasi- 

ana 279 

200.  Valuta    elongata 279 

201.  Nautilus    Danicus. . . .  280 

202.  Ancyloceras     Mather- 

onianus 281 

203.  Turrilites    catenatus . .  282 

204.  Forms   of    Cretaceous 

Ammonitidce 282 

205.  Belemnitella      mucro- 

nata 283 

206.  Tooth  of  Hybodus. . .   284 

207.  Fin-spine  of  Hybodus  284 

208.  Beryx  Lewesiensis  and 

Osmeroides  Mantelli  284 

209.  Teeth    of    Iguanodon    286 

210.  Skull  of  Mosasaurus- 

Camperi 287 

211.  Chelone    Benstedi 289 

212.  Jaws  and  vertebrae  of 

Odontornithes 291 

213.  Fruit  of  Nipadites 300 


214.  Nummulina    l&vigata    301 

215.  Turbinolia     sulcata...  302 

216.  Cardita  planicosta 303 

217.  Typhis    tubifer 303 

218.  Cypraa    elegans 303 

219.  Certhium   hexagonum   304 

220.  Limnaa  pyramidalis. .   304 

221.  Physa    columnaris 304 

222.  Cyclostoma    Arnoudii    304 

223.  Rhombus    minimus...  305 

224.  Otodus     obliquus 306 

225.  Myliobatis   Edwardsii   306 

226.  Upper  jaw  of  Alliga- 

tor      307 

227.  Skull       of       Odonto- 

pteryx  toliapicus 308 

228.  Zeuglodon  cetoides. . .  310 

229.  Palaotherium        mag- 

num, restored 311 

230.  Feet  of  Equida 312 

231.  Amplotherium       com- 

mune     313 

232.  Skull      of     Dinoceras 

mirabilis 314 

233.  Vespertilio      Parisien- 

sis.. 315 

234.  Miocene     Palms 319 

235.  Platanus    aceroides...  320 

236.  Cinnamomum        poly- 

morphum 320 

237.  Texularia    Meyeriana    322 

238.  Scutella  subrotunda..    323 

239.  Hyalea    Orbignyana..    323 

240.  Tooth  of  Oxyrhina..   324 

241.  Tooth     of     Carcharo- 

don 324 

242.  Andrias    Scheuchzeri    325 

243.  Skull  of  Brontother- 
ium    ingens 327 

244.  Hippopotamus    Sival- 

ensis 329 

245.  Skull   of   Sivatherium    330 

246.  Skull  of  Deinotherium    331 

247.  Tooth       of       Elephas 

planifrons      and      of 
Mastodon   Sivalensis  332 

248.  Jaw  of  Pliopithecus..  334 

249.  Rhinoceros      Etruscus 

and  R.  megarhinus..  339 

250.  Molar  tooth   of  Mas- 

todon   Arvernensis . .  341 

251.  Molar    tooth   of    Ele- 

phas   meridionalis . . .  342 


LIST  OF  ILLUSTRATIONS. 


252.  Molar    tooth    of    Ele- 

phas   antiquus 342 

253.  Skull     and     tooth     of 

Machairodus     cultri- 
dens 343 

254.  Pecten    Islandicus 35 l 

255.  Diagram  of  high-level 

and  low-level  gravels  353 

256.  Diagrammatic    section 

of    Cave 356 

257.  Dinornis  elephantopus  360 

258.  Skull  of  Diprotodon..  362 

259.  Skull  of  Thylacoleo..  362 

260.  Skeleton    of    Megath- 

erium      363 

261.  Skeleton  of  Mylodon  365 


262.  Glyptodon    clavipes...  365 

263.  Skull    of     Rhinoceros 

tichorhinus 366 

264.  Skeleton     of     Cervus 

megaceros 368 

265.  Skull    of    Bos    primi- 

genius 369 

266.  Skeleton  of  Mammoth  371 

267.  Molar  tooth  of  Mam- 

moth       372 

268.  Skull  of  Ursus  spelaus  373 

269.  Skull  of  Hyama  spel- 

(ua 374 

270.  Lower   jaw   of    Trog- 

ontherium  Cuvieri...  375 


PART     I. 


PRINCIPLES  OF  PALEONTOLOGY. 


THE 
ANCIENT     LIFE-HISTORY 

OF 

THE    EARTH. 


INTRODUCTION. 

THE  LAWS  OF  GEOLOGICAL  ACTION. 

UNDER  the  general  title  of  "  Geology "  are  usually  included  at 
least  two  distinct  branches  of  inquiry,  allied  to  one  another  in 
the  closest  manner,  and  yet  so  distinct  as  to  be  largely  capable 
of  separate  study.  Geology*  in  its  strictest  sense,  is  the  science 
which  is  concerned  with  the  investigation  of  the  materials  which 
compose  the  earth,  the  methods  in  which  those  materials  have 
been  arranged,  and  the  causes  and  modes  of  origin  of  these 
arrangements.  In  this  limited  aspect,  Geology  is  nothing  more 
than  the  Physical  Geography  of  the  past,  just  as  Physical  Geog- 
raphy is  the  Geology  of  to-day;  and  though  it  has  to  call  in 
the  aid  of  Physics,  Astronomy,  Mineralogy,  Chemistry,  and 
other  allies  more  remote,  it  is  in  itself  a  perfectly  distinct  and 
individual  study.  One  has,  however,  only  to  cross  the  thresh- 
old of  Geology  to  discover  that  the  field  and  scope  of  the 
science  cannot  be  thus  rigidly  limited  to  purely  physical  prob- 
lems. The  study  of  the  physical  development  of  the  earth 
throughout  past  ages  brings  us  at  once  in  contact  with  the 
forms  of  animal  and  vegetable  life  which  peopled  its  surface  in 
bygone  epochs,  and  it  is  found  impossible  adequately  to  com- 

*y  *  Gr.  gf,  the  earth ;  logos,  a  discourse. 


2  PRINCIPLES  OF  PALEONTOLOGY. 

prebend  the  former,  unless  we  possess  some  knowledge  of  the 
latter.  However  great  its  physical  advantages  may  be,  Geology 
remains  imperfect  till  it  is  wedded  with  Palaeontology,*  a  study 
which  essentially  belongs  to  the  vast  complex  of  the  Biologi- 
cal Sciences,  but  at  the  same  time  has  its  strictly  geological 
side.  Dealing,  as  it  does,  wholly  with  the  consideration  of 
such  living  beings  as  do  not  belong  exclusively  to  the  present 
order  of  things,  Palaeontology  is,  in  reality,  a  branch  of  Natu- 
ral History,  and  may  be  regarded  as  substantially  the  Zoology 
and  Botany  of  the  past.  It  is  the  ancient  life-history  of  the 
earth,  as  revealed  to  .us  by  the  labors  of  palaeontologists,  with 
which  we  have  mainly  to  do  here;  but  before  entering  upon 
this,  there  are  some  general  questions,  affecting  Geology  and 
Palaeontology  alike,  which  may  be  very  briefly  discussed. 

The  working  geologist,  dealing  in  the  main  with  purely  phys- 
ical problems,  has  for  his  object  to  determine  the  material 
structure  of  the  earth,  and  to  investigate,  as  far  as  may  be,  the 
long  chain  of  causes  of  which  that  structure  is  the  ultimate  re- 
sult. No  wider  or  more  extended  field  of  inquiry  could  be 
found;  but  philosophical  geology  is  not  content  with  this.  At 
all  the  confines  of  his  science,  the  transcendental  geologist 
finds  himself  confronted  with  some  of  the  most  stupendous 
problems  which  have  ever  engaged  the  restless  intellect  of  hu- 
manity. The  origin  and  primaeval  constitution  of  the  terrestrial 
globe,  the  laws  and  geologic  action  through  long  ages  of  vicis- 
situde and  development,  the  origin  of  life,  the  nature  and  source 
of  the  myriad  complexities  of  living  beings,  the  advent  of  man, 
possibly  even  the  future  history  of  the  earth,  are  amongst  the 
questions  with  which  the  geologist  has  to  grapple  in  his  higher 
capacity. 

These  are  problems  which  have  occupied  the  attention  of 
philosophers  in  every  age  of  the  world,  and  in  periods  long 
antecedent  to  the  existence  of  a  science  of  geology.  The  mere 
existence  of  cosmogonies  in  the  religion  of  almost  every  nation, 
both  ancient  and  modern,  is  a  sufficient  proof  of  the  eager  de- 
sire of  the  human  mind  to  know  something  of  the  origin  of  the 
earth  on  which  we  tread.  Every  human  being  who  has  gazed 
on  the  vast  panorama  of  the  universe,  though  it  may  have  been 
but  with  the  eyes  of  a  child,  has  felt  the  longing  to  solve,  how- 
ever imperfectly,  "the  riddle  of  the  painful  earth,"  and  has, 
consciously  or  unconsciously,  elaborated  some  sort  of  a  theory 
as  to  the  why  and  wherefore  of  what  he  sees.  Apart  from  the 
*  Gr.  palaios,  ancient ;  onto,  beings ;  logos,  discourse. 


THE  LAWS  OF  GEOLOGICAL  ACTION.  3 

profound  and  perhaps  inscrutable  problems  which  lie  at  the 
bottom  of  human  existence,  men  have  in  all  ages  invented 
theories  to  explain  the  common  phenomena  of  the  material  uni- 
verse;  and  most  of  these  theories,  however  varied  in  their  de- 
tails, turn  out  on  examination  to  have  a  common  root,  and  to 
be  based  on  the  same  elements.  Modern  geology  has  its  own 
theories  on  the  same  subject,  and  it  will  be  well  to  glance  for 
a  moment  at  the  principles  underlying  the  old  and  the  new 
views. 

It  has  been  maintained,  as  a  metaphysical  hypothesis,  that 
there  exists  in  the  mind  of  man  an  inherent  principle,  in  virtue 
of  which  he  believes  and  expects  that  what  has  been,  will  be; 
and  that  the  course  of  nature  will  be  a  continuous  and  unin- 
terrupted one.  So  far,  however,  from  any  such  belief  existing 
as  a  necessary  consequence  of  the  constitution  of  the  human 
mind,  the  real  fact  seems  to  be  that  the  contrary  belief  has 
been  almost  universally  prevalent.  In  all  old  religions,  and  in 
the  philosophical  systems  of  almost  all  ancient  nations,  the  order 
of  the  universe  has  been  regarded  as  distinctly  unstable,  mu- 
table, and  temporary.  A  beginning  and  an  end  have  always 
been  assumed,  and  the  course  of  terrestrial  events  between  these 
two  indefinite  points  has  been  regarded  as  liable  to  constant 
interruption  by  revolutions  and  catastrophes  of  different  kinds, 
in  many  cases  emanating  from  supernatural  sources.  Few  of 
the  more  ancient  theological  creeds,  and  still  fewer  of  the 
ancient  philosophies,  attained  body  and  shape  without  contain- 
ing, in  some  form  or  other,  the  belief  in  the  existence  of  peri- 
odical convulsions,  and  of  alternating  cycles  of  destruction  and 
repair. 

That  geology,  in  its  early  infancy,  should  have  become  im- 
bued with  the  spirit  of  this  belief,  is  no  more  than  might  have 
been  expected;  and  hence  arose  the  at  one  time  powerful  and 
generally-accepted  doctrine  of  "  Catastrophism."  That  the  suc- 
cession of  phenomena  upon  the  globe,  whereby  the  earth's  crust 
had  assumed  the  configuration  and  composition  which  we  find 
it  to  possess,  had  been  a  discontinuous  and  broken  succession, 
was  the  almost  inevitable  conclusion  of  the  older  geologists. 
Everywhere  in  their  study  of  the  rocks  they  met  with  appar- 
ently impassable  gaps,  and  breaches  of  continuity  that  could 
not  be  bridged  over.  Everywhere  they  found  themselves  con- 
ducted abruptly  from  one  system  of  deposits  to  others  totally 
different  in  mineral  character  or  in  stratigraphical  position. 
Everywhere  they  discovered  that  well-marked  and  easily  recog- 


4  PRINCIPLES  OF  PALAEONTOLOGY. 

nizable  groups  of  animals  and  plants  were  succeeded,  without 
the  intermediation  of  any  obvious  lapse  of  time,  by  other  assem- 
blages of  organic  beings  of  a  different  character.  Everywhere 
they  found  evidence  that  the  earth's  crust  had  undergone  changes 
of  such  magnitude  as  to  render  it  seemingly  irrational  to  sup- 
pose that  they  could  have  been  produced  by  any  process  now  in 
existence.  If  we  add  to  the  above  the  prevalent  belief  of  the 
time  as  to  the  comparative  brevity  of  the  period  which  had 
elapsed  since  the  birth  of  the  globe,  we  can  readily  understand 
the  general  acceptance  of  some  form  of  catastrophism  amongst 
the  earlier  geologists. 

As  regards  its  general  sense  and  substance,  the  doctrine  of 
catastrophism  held  that  the  history  of  the  earth,  since  first  it 
emerged  from  the  primitive  chaos,  had  been  one  of  periods  of 
repose,  alternating  with  catastrophes  and  cataclysms  of  a  more 
or  less  violent  character.  The  periods  of  tranquillity  were  sup- 
posed to  have  been  long  and  protracted ;  and  during  each  of 
them  it  was  thought  that  one  of  the  great  geological  "  forma- 
tions "  was  deposited.  In  each  of  these  periods,  therefore,  the 
condition  of  the  earth  was  supposed  to  be  much  the  same  as  it 
is  now — sediment  was  quietly  accumulated  at  the  bottom  of  the 
sea,  and  animals  and  plants  flourished  uninterruptedly  and  in 
successive  generations.  Each  period  of  tranquillity,  however,  was 
believed  to  have  been,  sooner  or  later,  put  an  end  to  by  a  sud- 
den and  awful  convulsion  of  nature,  ushering  in  a  brief  and 
paroxysmal  period,  in  which  the  great  physical  forces  were 
unchained  and  permitted  to  spring  into  a  portentous  activity. 
The  forces  of  subterranean  fire,  with  their  concomitant  phe- 
nomena of  earthquake  and  volcano,  were  chiefly  relied  upon  as 
the  efficient  cause  of  these  periods  of  spasm  and  revolution. 
Enormous  elevations  of  portions  of  the  earth's  crust  were  thus 
believed  to  be  produced,  accompanied  by  corresponding  and 
equally  gigantic  depressions  of  other  portions.  In  this  way  new 
ranges  of  mountains  were  produced,  and  previously  existing 
ranges  levelled  with  the  ground,  seas  were  converted  into  dry 
land,  and  continents  buried  beneath  the  ocean — catastrophe  fol- 
lowing catastrophe,  till  the  earth  was  rendered  uninhabitable, 
and  its  races  of  animals  and  plants  were  extinguished,  never  to 
reappear  in  the  same  form.  Finally,  it  was  believed  that  this 
feverish  activity  ultimately  died  out,  and  that  the  ancient  peace: 
once  more  came  to  reign  upon  the  earth.  As  the  abnormal 
throes  and  convulsions  began  to  be  relieved,  the  dry  land  and 
sea  once  more  resumed  their  relations  of  stability,  the  condi- 


THE  LAWS  OF  GEOLOGICAL  ACTION.  5 

tions  of  life  were  once  more  established,  and  new  races  of  ani- 
mals and  plants  sprang  into  existence,  to  last  until  the  super- 
vention of  another  fever-fit. 

Such  is  the  past  history  of  the  globe,  as  sketched  for  us,  in 
alternating  scenes  of  fruitful  peace  and  revolutionary  destruc- 
tion, by  the  earlier  geologists.  As  before  said,  we  cannot  won- 
der at  the  former  general  acceptance  of  Catastrophistic  doc- 
trines. Even  in  the  light  of  our  present  widely-increased 
knowledge,  the  series  of  geological  monuments  remains  a  broken 
and  imperfect  one;  nor  can  we  ever  hope  to  fill  up  completely 
the  numerous  gaps  with  which  the  geological  record  is  defaced. 
Catastrophism  was  the  natural  method  of  accounting  for  these 
gaps,  and,  as  we  shall  see,  it  possesses  a  basis  of  truth.  At  pres- 
ent, however,  catastrophism  may  be  said  to  be  nearly  extinct,  and 
its  place  is  taken  by  the  modern  doctrine  of  "Continuity"  or 
"  Uniformity " — a  doctrine  with  which  the  name  of  Lyell  must 
ever  remain  imperishably  associated. 

The  fundamental  thesis  of  the  doctrine  of  Uniformity  is, 
that,  in  spite  of  all  apparent  violations  of  continuity,  the  se- 
quence of  geological  phenomena  has  in  reality  been  a  regular 
and  uninterrupted  one;  and  that  the  vast  changes  which  can  be 
shown  to  have  passed  over  the  earth  in  former  periods  have 
been  the  result  of  the  slow  and  ceaseless  working  of  the  ordi- 
nary physical  forces — acting  with  no  greater  intensity  than  they 
do  now,  but  acting  through  enormously  prolonged  periods.  The 
essential  element  in  the  theory  of  Continuity  is  to  be  found  in 
the  allotment  of  indefinite  time  for  the  accomplishment  of  the 
known  series  of  geological  changes.  It  is  obviously  the  case, 
namely,  that  there  are  two  possible  explanations  of  all  phenom- 
ena which  lie  so  far  concealed  in  "the  dark  backward  and 
abysm  of  time,"  that  we  can  have  no  direct  knowledge  of  the 
manner  in  which  they  were  produced.  We  may,  on  the  one 
hand,  suppose  them  to  be  the  result  of  some  very  powerful  cause, 
acting  through  a  short  period  of  time.  That  is  Catastrophism. 
Or,  we  may  suppose  them  to  be  caused  by  a  much  weaker  force 
operating  through  3  proportionately  prolonged  period.  This  is 
the  view  of  the  Uniformitarians.  It  is  a  question  of  energy 
versus  time;  and  it  is  time  which  is  the  true  element  of  the  case. 
An  earthquake  may  remove  a  mountain  in  the  course  of  a  few 
seconds;  but  the  dropping  of  the  gentle  rain  will  do  the  same, 
if  we  extend  its  operations  over  a  millennium.  And  this  is  true 
of  all  agencies  which  are  now  at  work,  or  ever  have  been  at 
work,  upon  our  planet.  The  Catastrophists,  believing  that  the 


6  PRINCIPLES  OF  PALAEONTOLOGY. 

globe  is  but,  as  it  were,  the  birth  of  yesterday,  were  driven  of 
necessity  to  the  conclusion  that  its  history  had  been  checkered 
by  the  intermittent  action  of  paroxysmal  and  almost  inconceiva- 
bly potent  forces.  The  Uniformitarians,  on  the  other  hand, 
maintaining  the  "  adequacy  of  existing  causes,"  and  denying  that 
the  known  physical  forces  ever  acted  in  past  time  with  greater 
intensity  than  they  do  at  present,  are,  equally  of  necessity,  driven 
to  the  conclusion  that  the  world  is  truly  in  its  "  hoary  eld,"  and 
that  its  present  state  is  really  the  result  of  the  tranquil  and 
regulated  action  of  known  forces  through  unnumbered  and  in- 
numerable centuries. 

The  most  important  point  for  us,  in  the  present  connection, 
is  the  bearing  of  these  opposing  doctrines  upon  the  question  as 
to  the  origin  of  the  existing  terrestrial  order.  On  any  doctrine 
of  uniformity  that  order  has  been  evolved  slowly,  and,  accord- 
ing to  law,  from  a  pre-existing  order.  Any  doctrine  of  catas- 
trophism,  on  the  other  hand,  carries  with  it,  by  implication,  the 
belief  that  the  present  order  of  things  was  brought  about  sud- 
denly and  irrespective  of  any  pre-existent  order;  and  it  is 
important  to  hold  clear  ideas  as  to  which  of  these  beliefs  is  the 
true  one.  In  the  first  place,  we  may  postulate  that  the  world 
had  a  beginning,  and,  equally,  that  the  existing  terrestrial  order 
had  a  beginning.  However  far  back  we  may  go,  geology  does 
not,  and  cannot,  reach  the  actual  beginning  of  the  world;  and 
we  are,  therefore,  left  simply  to  our  own  speculations  on  this 
point.  With  regard,  however,  to  the  existing  terrestrial  order, 
a  great  deal  can  be  discovered,  and  to  do  so  is  one  of  the  prin- 
cipal tasks  of  geological  science.  The  first  steps  in  the  produc- 
tion of  that  order  lie  buried  in  the  profound  and  unsearchable 
depths  of  a  past  so  prolonged  as  to  present  itself  to  our  finite 
minds  as  almost  an  eternity.  The  last  steps  are  in  the  prophetic 
future,  and  can  be  but  dimly  guessed  at.  Between  the  remote 
past  and  the  distant  future,  we  have,  however,  a  long  period 
which  is  fairly  open  to  inspection ;  and  in  saying  a  "  long " 
period,  it  is  to  be  borne  in  mind  that  this  term  is  used  in  its 
geological  sense.  Within  this  period,  enormously  long  as  it  is 
when  measured  by  human  standards,  we  can  trace  with  reason- 
able certainty  the  progressive  march  of  events,  and  can  deter- 
mine the  laws  of  geological  action,  by  which  the  present  order 
of  things  has  been  brought  about. 

The  natural  belief  on  this  subject  doubtless  is,  that  the 
world,  such  as  we  now  see  it,  possessed  its  present  form  and 
configuration  from  the  beginning.  Nothing  can  be  more  nat- 


THE  LAWS  OF  GEOLOGICAL  ACTION.  7 

ural  than  the  belief  that  the  present  continents  and  oceans  have 
always  been  where  they  are  now ;  that  we  have  always  had  the 
same  mountains  and  plains;  that  our  rivers  have  always  had 
their  present  courses,  and  our  lakes  their  present  positions,  that 
our  climate  has  always  been  the  same;  and  that  our  animals 
and  plants  have  always  been  identical  with  tnose  now  familiar 
to  us.  Nothing  could  be  more  natural  than  such  a  belief,  and 
nothing  could  be  further  removed  from  the  actual  truth.  On 
the  contrary,  a  very  slight  acquaintance  with  geology  shows  us, 
in  the  words  of  Sir  John  Herschel,  that  "the  actual  configura- 
tion of  our  continents  and  islands,  the  coast-lines  of  our  maps, 
the  direction  and  elevation  of  our  mountain-chains,  the  courses 
of  our  rivers,  and  the  soundings  of  our  oceans,  are  not  things 
primordially  arranged  in  the  construction  of  our  globe,  but  re- 
sults of  successive  and  complex  actions  on  a  former  state  of 
things;  that,  again,  of  similar  actions  on  another  still  more  re- 
mote: and  so  on,  till  the  original  and  really  permanent  state  is 
pushed  altogether  out  of  sight  and  beyond  the  reach  even  of 
imagination ;  while  on  the  other  hand,  a  similar,  and,  as  far  as 
we  can  see,  interminable  vista  is  opened  out  for  the  future,  by 
which  the  habitability  of  our  planet  is  secured  amid  the  total 
abolition  on  it  of  the  present  theatres  of  terrestrial  life." 

Geology,  then,  teaches  us  that  the  physical  features  which 
now  distinguish  the  earth's  surface  have  been  produced  as  the 
ultimate  result  of  an  almost  endless  succession  of  precedent 
changes.  Palaeontology  teaches  us,  though  not  yet  in  such  as- 
sured accents,  the  same  lesson.  Our  present  animals  and  plants 
have  not  been  produced,  in  their  innumerable  forms,  each  as  we 
now  know  it,  as  the  sudden,  collective,  and  simultaneous  birth 
of  a  renovated  world.  On  the  contrary,  we  have  the  clearest 
evidence  that  some  of  our  existing  animals  and  plants  made 
their  appearance  upon  the  earth  at  a  much  earlier  period  than 
others.  In  the  confederation  of  animated  nature  some  races 
can  boast  of  an  immemorial  antiquity,  whilst  others  are  com- 
parative parvenus.  We  have  also  the  clearest  evidence  that  the 
animals  and  plants  which  now  inhabit  the  globe  have  been  pre- 
ceded, over  and  over  again,  by  other  different  assemblages  of 
animals  and  plants,  which  have  flourished  in  successive  periods 
of  the  earth's  history,  have  reached  their  culmination,  and  then 
have  given  way  to  a  fresh  series  of  living  beings.  We  have, 
finally,  the  clearest  evidence  that  these  successive  groups  of 
animals  and  plants  (faunae  and  florae)  are  to  a  greater  or  less 
extent  directly  connected  with  one  another.  Each  group  is,  to 


8  PRINCIPLES  OF  PALEONTOLOGY. 

a  greater  or  less  extent,  the  lineal  descendant  of  the  group  which 
immediately  preceded  it  in  point  of  time,  and  is  more  or  less 
fully  concerned  with  giving  origin  to  the  group  which  immedi- 
ately follows  it.  That  this  law  of  "  evolution "  has  prevailed 
to  a  great  extent  is  quite  certain ;  but  it  does  not  meet  all  the 
exigencies  of  the  case,  and  it  is  probable  that  its  action  has  been 
supplemented  by  some  still  unknown  law  of  a  different  character. 

We  shall  have  to  consider  the  question  of  geological  "con- 
tinuity" again.  In  the  meanwhile,  it  is  sufficient  to  state  that 
this  doctrine  is  now  almost  universally  accepted  as  the  basis  of 
all  inquiries,  both  in  the  domain  of  geology  and  that  of  palaeon- 
tology. The  advocates  of  continuity  possess  one  of  immense 
advantage  over  those  who  believe  in  violent  and  revolutionary 
convulsions,  that  they  call  into  play  only  agencies  of  which  we 
have  actual  knowledge.  We  know  that  certain  forces  are  now 
at  work,  producing  certain  modifications  in  the  present  condi- 
tion of  the  globe ;  and  we  know  that  these  forces  are  capable  of 
producing  the  vastest  of  the  changes  which  geology  brings  under 
our  consideration,  provided  we  assign  a  time  proportionately 
vast  for  their  operation.  On  the  other  hand,  the  advocates  of 
catastrophism,  to  make  good  their  views,  are  compelled  to  invoke 
forces  and  actions,  both  destructive  and  restorative,  of  which  we 
have,  and  can  have,  no  direct  knowledge.  They  endow  the 
whirlwind  and  the  earthquake,  the  central  fire  and  the  rain  from 
heaven,  with  powers  as  mighty  as  ever  imagined  in  fable,  and 
they  build  up  the  fragments  of  a  repeatedly  shattered  world  by 
the  intervention  of  an  intermittently  active  creative  power. 

It  should  not  be  forgotten,  however,  that  from  one  point  of 
view  there  is  a  truth  in  catastrophism  which  is  sometimes  over- 
looked by  the  advocates  of  continuity  and  uniformity.  Catas- 
trophism has,  as  its  essential  feature,  the  proposition  that  the 
known  and  existing  forces  of  the  earth  at  one  time  acted  with 
much  greater  intensity  and  violence  than  they  do  at  present, 
and  they  carry  down  the  period  of  this  excessive  action  to  the 
commencement  of  the  present  terrestrial  order.  The  Uniformi- 
tarians,  in  effect,  deny  this  proposition,  at  any  rate  as  regards 
any  period  of  the  earth's  history  of  which  we  have  actual  cog- 
nizance. If,  however,  the  "  nebular  hypothesis "  of  the  origin 
of  the  universe  be  well  founded — as  is  generally  admitted — then, 
beyond  question,  the  earth  is  a  gradually  cooling  body,  which 
has  at  one  time  been  very  much  hotter  than  it  is  at  present. 
There  has  been  a  time,  therefore,  in  which  the  igneous  forces  of 
the  earth,  to  which  we  owe  the  phenomena  of  earthquakes  and 


THE  LAWS  OF  GEOLOGICAL  ACTION.  9 

volcanoes,  must  have  been  far  more  intensely  active  than  we 
can  conceive  of  from  anything  that  we  can  see  at  the  present 
day.  By  the  same  hypothesis,  the  sun  is  a  cooling  body,  and 
must  have  at  one  time  possessed  a  much  higher  temperature 
than  it  has  at  present.  But  increased  heat  of  the  sun  would 
seriously  alter  the  existing  conditions  affecting  the  evaporation 
and  precipitation  of  moisture  on  our  earth;  and  hence  the 
aqueous  forces  may  also  have  acted  at  one  time  more  power- 
fully than  they  do  now.  The  fundamental  principle  of  catas- 
trophism  is,  therefore,  not  wholly  vicious;  and  we  have  reason 
to  think  that  there  must  have  been  periods — very  remote,  it  ^s 
true,  and  perhaps  unrecorded  in  the  history  of  the  earth — in 
which  the  known  physical  forces  may  have  acted  with  an  inten- 
sity much  greater  than  direct  observation  would  lead  us  to 
imagine.  And  this  may  be  believed,  altogether  irrespective  of 
those  great  secular  changes  by  which  hot  or  cold  epochs  are 
produced,  and  which  can  hardly  be  called  "  catastrophistic,"  as 
they  are  produced  gradually,  and  are  liable  to  recur  at  definite 
intervals. 

Admitting,  then,  that  there  is  a  truth  at  the  bottom  of  the 
once  current  doctrines  of  catastrophism,  still  it  remains  certain 
that  the  history  of  the  earth  has  been  one  of  law  in  all  past  time, 
as  it  is  now.  Nor  need  we  shrink  back  affrighted  at  the  vast- 
ness  of  the  conception — the  vaster  for  its  very  vagueness — that 
we  are  thus  compelled  to  form  as  to  the  duration  of  geological 
time.  As  we  grope  our  way  backward  through  the  dark  laby- 
rinth of  the  ages,  epoch  succeeds  to  epoch,  and  period  to  period, 
each  looming  more  gigantic  in  its  outlines  and  more  shadowy 
in  its  features,  as  it  rises,  dimly  revealed,  from  the  mist  and 
vapor  of  an  older  and  ever-older  past.  It  is  useless  to  add 
century  to  century  or  millennium  to  millennium.  When  we  pass 
a  certain  boundary-line,  which,  after  all,  is  reached  very  soon, 
figures  cease  to  convey  to  our  finite  faculties  any  real  notion  of 
the  periods  with  which  we  have  to  deal.  The  astronomer  can 
employ  material  illustrations  to  give  form  and  substance  to  our 
conceptions  of  celestial  space;  but  such  a  resource  is  unavail- 
able to  the  geologist.  The  few  thousand  years  of  which  we  have 
historical  evidence  sink  into  absolute  insignificance  besides  the 
unnnumbered  aeons  which  unroll  themselves  one  by  one  as  we 
penetrate  the  dim  recesses  of  the  past,  and  decipher  with  feeble 
vision  the  ponderous  volumes  in  which  the  record  of  the  earth 
is  written.  Vainly  does  the  strained  intellect  seek  to  overtake 
an  ever-receding  commencement,  and  toil  to  gain  some  adequate 


io  PRINCIPLES  OF  PALEONTOLOGY. 

grasp  of  an  apparently  endless  succession.  A  beginning  there 
must  have  been,  though  we  can  never  hope  to  fix  its  point.  Even 
speculation  droops  her  wings  in  the  attenuated  atmosphere  of  a 
past  so  remote,  and  the  light  of  imagination  is  quenched  in  the 
darkness  of  a  history  so  ancient.  In  time,  as  in  space,  the  con- 
fines of  the  universe  must  ever  remain  concealed  from  us;  and 
of  the  end  we  know  no  more  than  of  the  beginning.  Inconceiv- 
able as  is  to  us  the  lapse  of  "  geological  time,"  it  is  no  more  than 
"a  mere  moment  of  the  past,  a  mere  infinitesimal  portion  of 
eternity."  Well  may  "  the  human  heart,  that  weeps  and  trem- 
bles," say,  with  Richter's  pilgrim  through  celestial  space,  "  I  will 
go  no  farther;  for  the  spirit  of  man  acheth  with  this  infinity. 
Insufferable  is  the  glory  of  God.  Let  me  lie  down  in  the  grave, 
and  hide  me  from  the  persecution  of  the  Infinite,  for  end,  I 
see,  there  is  none. " 


CHAPTER  I. 
THE  SCOPE  AND  MATERIALS  OF  PALAEONTOLOGY. 

The  study  of  the  rock-masses  which  constitute  the  crust  of 
the  earth,  if  carried  out  in  the  methodical  and  scientific  manner 
of  the  geologist,  at  once  brings  us,  as  has  been  before  remarked, 
in  contact  with  the  remains  or  traces  of  living  beings  which 
formerly  dwelt  upon  the  globe.  Such  remains  are  found,  in 
greater  or  less  abundance,  in  the  great  majority  of  rocks;  and 
they  are  not  only  of  great  interest  in  themselves,  but  they  have 
proved  of  the  greatest  importance  as  throwing  light  upon  vari- 
ous difficult  problems  in  geology,  in  natural  history,  in  botany, 
and  in  philosophy.  Their  study  constitutes  the  science  of  palaeon- 
tology; and  though  it  is  possible  to  proceed  to  a  certain  length 
in  geology  and  zoology  without  much  palaeontological  knowledge, 
it  is  hardly  possible  to  attain  to  a  satisfactory  general  acquaint- 
ance with  either  of  these  subjects  without  having  mastered  the 
leading  facts  of  the  first.  Similarly,  it  is  not  possible  to  study 
palaeontology  without  some  acquaintance  with  both  geology  and 
natural  history. 

PALAEONTOLOGY,  then,  is  the  science  which  treats  of  the  liv- 
ing beings,  whether  animal  or  vegetable,  which  have  inhabited 


THE  SCOPE  OF  PALEONTOLOGY.  n 

the  earth  during  past  periods  of  its  history.  Its  object  is  to 
eludicate,  as  far  as  may  be,  the  structure,  mode  of  existence, 
and  habits  of  all  such  ancient  forms  of  life;  to  determine  their 
position  in  the  scale  of  organized  beings ;  to  lay  down  the  geo- 
graphical limits  within  which  they  flourished;  and  to  fix  the 
period  of  their  advent  and  disappearance.  It  is  the  ancient  life- 
history  of  the  earth;  and  were  its  record  complete,  it  would 
furnish  us  with  a  detailed  knowledge  of  the  form  and  relations 
of  all  the  animals  and  plants  which  have  at  any  period  flourished 
upon  the  land-surfaces  of  the  globe  or  inhabited  its  waters ;  it 
would  enable  us  to  determine  precisely  their  succession  in  time; 
and  it  would  place  in  our  hands  an  unfailing  key  to  the  prob- 
lems of  evolution.  Unfortunately,  from  causes  which  will  be 
subsequently  discussed,  the  palaeontological  record  is  extremely 
imperfect,  and  our  knowledge  is  interrupted  by  gaps,  which  not 
only  bear  a  large  proportion  to  our  solid  information,  but  which 
in  many  cases  are  of  such  a  nature  that  we  can  never  hope  to 
fill  them  up 

FOSSILS. — The  remains  of  animals  or  vegetables  which  we 
now  find  entombed  in  the  solid  rock,  and  which  constitute  the 
working  material  of  the  palaeontologist,  are  termed  "  fossils, "  * 
or  "  petrifactions. "  In  most  cases,  as  can  be  readily  understood, 
fossils  are  the  actual  hard  parts  of  animals  and  plants  which 
were  in  existence  when  the  rock  in  which  they  are  now  found 
was  being  deposited.  Most  fossils,  therefore,  are  of  the  nature 
of  the  shells  of  shell-fish,  the  skeletons  of  coral-zoophytes,  the 
bones  of  vertebrate  animals,  or  the  wood,  bark,  or  leaves  of 
plants.  All  such  bodies  are  more  or  less  of  a  hard  consistence 
to  begin  with,  and  are  capable  of  resisting  decay  for  a  longer  or 
shorter  time — hence  the  frequency  with  which  they  occur  in  the 
fossil  condition.  Strictly  speaking,  however,  by  the  term  "  fossil " 
must  be  understood  "  any  body,  or  the  traces  of  the  existence  of 
any  body,  whether  animal  or  vegetable,  which  has  been  buried 
in  the  earth  by  natural  causes"  (Lyell).  We  shall  find,  in  fact, 
that  many  of  the  objects  which  we  have  to  study  as  "fossils" 
have  never  themselves  actually  formed  parts  of  any  animal  or 
vegetable,  though  they  are  due  to  the  former  existence  of  such 
organisms,  and  indicate  what  was  the  nature  of  these.  Thus 
the  footprints  left  by  birds,  or  reptiles,  or  quadrupeds  upon  sand 
or  mud,  are  just  as  much  proofs  of  the  former  existence  of 
these  animals  as  would  be  bones,  feathers,  or  scales,  though  in 

*  Lat.  fossus,  dug  up. 


12  PRINCIPLES  OF  PALAEONTOLOGY. 

themselves  they  are  inorganic.  Under  the  head  of  fossils,  there- 
fore, come  the  footprints  of  air-breathing  vertebrate  animals; 
the  tracks,  trails,  and  burrows  of  sea-worms,  crustaceans,  or 
molluscs;  the  impressions  left  on  the  sand  by  stranded  jelly- 
fishes  ;  the  burrows  in  stone  or  wood  of  certain  shell-fish ;  the 
"  moulds "  or  "  casts "  of  shells,  corals,  and  other  organic  re- 
mains ;  and  various  other  bodies  of  a  more  or  less  similar  nature. 

FOSSILIZATION. — The  term  "  fossilization "  is  applied  to  all 
those  processes  through  which  the  remains  of  organized  beings 
may  pass  in  being  converted  into  fossils.  These  processes  are 
numerous  and  varied;  but  there  are  three  principal  modes  of 
fossilization  which  alone  need  be  considered  here.  In  the  first 
instance,  the  fossil  is  to  all  intents  and  purposes  an  actual  por- 
tion of  the  original  organized  being — such  as  a  bone,  a  shell,  or 
a  piece  of  wood.  In  some  rare  instances,  as  in  the  case  of  the 
body  of  the  Mammoth  discovered  embedded  in  ice  at  the  mouth 
of  the  Lena  in  Siberia,  the  fossil  may  be  preserved  almost  pre- 
cisely in  its  original  condition,  and  even  with  its  soft  parts  un- 
injured. More  commonly,  certain  changes  have  taken  place  in 
the  fossil,  the  principal  being  the  more  or  less  removal  of  the 
organic  matter  originally  present.  Thus  bones  become  light  and 
porous  by  the  removal  of  their  gelantine,  so  as  to  cleave  to  the 
tongue  on  being  applied  to  that  organ;  whilst  shells  become 
fragile,  and  lose  their  primitive  colors.  In  other  cases,  though 
practically  the  real  body  it  represents,  all  the  cavities  of  the 
fossil,  down  to  its  minutest  recesses,  may  have  become  infiltrated 
with  mineral  matter.  It  need  hardly  be  added,  that  it  is  in  the 
more  modern  rocks  that  we  find  the  fossils,  as  a  rule,  least 
changed  from  their  former  condition;  but  the  original  structure 
is  often  more  or  less  completely  retained  in  some  of  the  fossils 
from  even  the  most  ancient  formations. 

In  the  second  place,  we  very  frequently  meet  with  fossils  in 
the  state  of  "casts"  or  moulds  of  the  original  organic  body. 
What  occurs  in  this  case  will  be  readily  understood  if  we  imag- 
ine any  common  bivalve  shell,  as  an  Oyster,  or  Mussel,  or 
Cockle,  embedded  in  clay  or  mud.  If  the  clay  were  sufficiently 
soft  and  fluid,  the  first  thing  would  be  that  it  would  gain  access 
to  the  interior  of  the  shell,  and  would  completely  fill  up  the 
space  between  the  valves.  The  pressure,  also,  of  the  surround- 
ing matter  would  insure  that  the  clay  would  everywhere  ad- 
here closely  to  the  exterior  of  the  shell.  If  now  we  suppose  the 
clay  to  be  in  any  way  hardened  so  as  to  be  converted  into 
stone,  and  if  we  were  to  break  up  the  stone,  we  should  obviously 


THE  SCOPE  OF  PALEONTOLOGY.  13 

have  the  following  state  of  parts.  The  clay  which  filled  the 
shell  would  form  an  accurate  cast  of  the  interior  of  the  shell, 
and  the  clay  outside  would  give  us  an  exact  impression  or 
cast  of  the  exterior  of  the  shell  (fig.  i).  We  should  have,  then, 

two  casts,  an  interior  and  an 
exterior,  and  the  two  would 
be  very  different  to  one  another, 
since  the  inside  of  a  shell  is 
very  unlike  the  outside.  In 
the  case,  in  fact,  of  many  uni- 
valve shells,  the  interior  cast  or 
"  mould "  is  so  unlike  the  ex- 
terior cast,  or  unlike  the  shell 
Fig.  i.—Triffonia  longa,  showing  casts  itself,  that  it  may  be  difficult  to 

determine  the  true  origin  of  the 
former. 

It  only  remains  to  add  that  there  is  sometimes  a  further 
complication.  If  the  rock  be  very  porous  and  permeable  by 
water,  it  may  happen  that  the  original  shell  is  entirely  dissolved 
away,  leaving  the  interior  cast  loose,  like  the  kernel  of  a  nut, 
within  the  case  formed  by  the  exterior  cast.  Or  it  may  happen 
that  subsequent  to  the  attainment  of  this  state  of  things,  the 
space  thus  left  vacant  between  the  interior  and  exterior  cast — 
the  space,  that  is,  formerly  occupied  by  the  shell  itself — may  be 
filled  up  by  some  foreign  mineral  deposited  there  by  the  infil- 
tration of  water.  In  this  last  case  the  splitting  open  of  the 
rock  would  reveal  an  interior  cast,  an  exterior  cast,  and  finally 
a  body  which  would  have  the  exact  form  of  the  original  shell, 
but  which  would  be  really  a  much  later  formation,  and  which 
would  not  exhibit  under  the  microscope  the  minute  structure  of 
shell. 

In  the  third  class  of  cases  we  have  fossils  which  present 
with  the  greatest  accuracy  the  external  form,  and  even  some- 
times the  internal  minute  structure,  of  the  original  organic  body, 
but  which,  nevertheless,  are  not  themselves  truly  organic,  but 
have  been  formed  by  a  "  replacement "  of  the  particles  of  the 
primitive  organism  by  some  material  substance.  The  most  ele- 
gant example  of  this  is  afforded  by  fossil  wood  which  has  been 
"silicified"  or  converted  into  flint  (silex}.  ^n  such  cases  we 
have  fossil  wood  which  presents  the  rings  of  growth  and  fibrous 
structure  of  recent  wood,  and  which  under  the  microscope 
exhibits  the  minutest  vessels  which  characterize  ligneous  tissue, 
together  with  the  even  more  minute  markings  of  the  vessels 


U  PRINCIPLES  OF  PALEONTOLOGY. 

(fig.  2.)  The  whole,  however,  instead  of  being  composed 
of  the  original  carbonaceous  matter  of  wood,  is  now  converted 
into  flint.  The  only  explanation  that  can  be  given  of  this  by  no 
means  rare  phenomenon,  is  that  the  wood  must  have  undergone 
a  slow  process  of  decay  in  water  charged  with  silica  or  flint  in 
solution.  As  each  successive  particle  of  wood  was  removed 


Fig,  2. —Microscopic  section  of  the 
silicified  wood  of  a  Conifer  (Sequoia}  cut 
in  the  long  direction  of  the  fibres.  Post- 
tertiary?  Colorado.  (Original.) 


Fig.  3.— Microscopic  section  of  the  wood 
of  the  common  Larch  (Abies  larix),  cut 
in  the  long  direction  of  the  fibres.  In 
both  the  fresh  and  the  fossil  wood  (fig. 
2)  are  seen  the  discs  characteristic  of  con- 
iferous wood.  (Original.) 


by  decay,  its  place  was  taken  by  a  particle  of  flint  deposited 
from  the  surrounding  water,  till  ultimately  the  entire  wood  was 
silicified.  The  process,  therefore,  resembles  what  would  take 
place  if  we  were  to  pull  down  a  house  built  of  brick  by  succes- 
sive bricks,  replacing  each  brick  as  removed  by  a  piece  of  stone 
of  precisely  the  same  size  and  form.  The  result  of  this  would 
be  that  the  house  would  retain  its  primitive  size,  shape,  and  out- 
line, but  it  would  finally  have  been  converted  from  a  house  of 
brick  into  a  house  of  stone.  Many  other  fossils  besides  wood — 
such  as  shells,  corals,  sponges,  &c. — are  often  found  silicified; 
and  this  may  be  regarded  as  the  commonest  form  of  fossiliza- 
tion  by  replacement.  In  other  cases,  however,  though  the  prin- 
ciple of  the  process  is  the  same,  the  replacing  substance  may  be 
iron  pyrites,  oxide  of  iron,  sulphur,  malachite,  magnesite,  talc, 
&c. ;  but  it  is  rarely  that  the  replacement  with  these  minerals  is 
so  perfect  as  to  preserve  the  more  delicate  details  of  internal 
structure. 


CHAPTER  II. 

THE  FOSSILIFEROUS  ROCKS. 

Fossils  are  found  in  rocks,  though  not  universally  or  pro- 
miscuously ;  and  it  is  therefore  necessary  that  the  palaeonto- 
logist should  possess  some  acquaintance  with,  at  any  rate,  those 
rocks  which  yield  organic  remains,  and  which  are  therefore 
said  to  be  "  fossiliferous.  "  In  geological  language,  all  the  ma- 
terials which  enter  into  the  composition  of  the  solid  crust  of 
the  earth,  be  their  texture  what  it  may — from  the  most  impal- 
pable mud  to  the  hardest  granite — are  termed  "rocks;"  and  for 
our  present  purpose  we  may  divide  these  into  two  great  groups. 
In  the  first  division  are  the  Igneous  Rocks — such  as  the  lavas  and 
ashes  of  volcanoes — which  are  formed  within  the  body  of  the 
earth  itself,  and  which  owe  their  structure  and  origin  to  the 
action  of  heat.  The  Igneous  Rocks  are  formed  primarily  below 
the  surface  of  the  earth,  which  they  only  reach  as  the  result  of 
volcanic  action;  they  are  generally  destitute  of  distinct  "strati- 
fication," or  arrangement  in  successive  layers ;  and  they  do 
not  contain  fossils,  except  in  the  comparatively  rare  instances 
where  volcanic  ashes  have  enveloped  animals  or  plants  which 
were  living  in  the  sea  or  on  the  land  in  the  immediate  vicinity 
of  the  volcanic  focus.  The  second  great  division  of  rocks  is 
that  of  the  Fossiliferous,  Aqueous,  or  Sedimentary  Rocks.  These 
are  formed  at  the  surface  of  the  earth,  and,  as  implied  by  one 
of  their  names,  are  invariably  deposited  in  water.  They  are 
produced  by  vital  or  chemical  action,  or  are  formed  from  the 
"  sediment "  produced  by  the  disintegration  and  reconstruction 
of  previously  existing  rocks,  without  previous  solution ;  they 
mostly  contain  fossils ;  and  they  are  arranged  in  distinct  layers 
or  "  strata."  The  so-called  "  aerial "  rocks  which,  like  the  beds 
of  blown  sand,  have  been  formed  by  the  action  of  the  atmos- 
phere, may  also  contain  fossils;  but  they  are  not  of  such  im- 
portance as  to  require  special  notice  here. 

15 


i6 


PRINCIPLES  OF  PALEONTOLOGY. 


For  all  practical  purposes,  we  may  consider  that  the  Aque- 
ous Rocks  are  the  natural  cemetery  of  the  animals  and  plants 
of  bygone  ages;  arid  it  is  therefore  essential  that  the  palaeonto- 


Fi«r.  4.— Sketch  of  Carboniferous  strata  at  Kinghorn,  in  Fife,  showing  stratified  beds 
(limestone  and  shales)  surmounted  by  an  unstratified  mass  of  trap.    (Original). 


logical  student  should  be  acquainted  with  some  of  the  principal 
facts  as  to  their  physical  characters,  their  minute  structure 
and  mode  of  origin,  their  chief  varieties,  and  their  historical 
succession. 

The  Sedimentary  or  Fossiliferous  Rocks  form  the  greater 
portion  of  that  part  of  the  earth's  crust  which  is  open  to  our 
examination,  and  are  distinguished  by  the  fact  that  they  are 
regularly  "  stratified  "  or  arranged  in  distinct  and  definite  layers 
or  "  strata."  These  layers  may  consist  of  a  single  material,  as 
in  a  block  of  sandstone,  or  they  may  consist  of  different  ma- 
terials. When  examined  on  a  large  scale,  they  are  always  found 
to  consist  of  alternations  of  layers  of  different  mineral  com- 
position. We  may  examine  any  given  area,  and  find  in  it  noth- 
ing but  one  kind  of  rock — sandstone,  perhaps,  or  limestone. 


THE  FOSSILIFEROUS  ROCKS.  17 

In  all  cases,  however,  if  we  extend  our  examination  sufficiently 
far,  we  shall  ultimately  come  upon  different  rocks ;  and,  as 
a  general  rule,  the  thickness  of  any  particular  set  of  beds  is 
comparatively  small,  so  that  different  kinds  of  rock  alternate 
with  one  another  in  comparatively  small  spaces. 

As  regards  the  origin  of  the  Sedimentary  Rocks,  they  are 
for  the  most  part  "  derivative "  rocks,  being  derived  from  the 
wear  and  tear  of  pre-existent  rocks.  Sometimes,  however,  they 
owe  their  origin  to  chemical  or  vital  action,  when  they  would 
more  properly  be  spoken  of  simply  as  Aqueous  Rocks.  As  to 
their  mode  of  deposition,  we  are  enabled  to  infer  that  the  mate- 
rials which  compose  them  have  formerly  been  spread  out  by 
the  action  of  water,  from  what  we  see  going  on  every  day  at 
the  mouths  of  our  great  rivers,  and  on  a  smaller  scale  wherever 
there  is  running  water.  Every  stream,  where  it  runs  into  a 
lake  or  into  the  sea,  carries  with  it  a  burden  of  mud,  sand,  and 
rounded  pebbles,  derived  from  the  waste  of  the  rocks  which 


ft 


Fig.  5.— Diagram  to  illustrate  the  formation  of  sedimentary  deposits  at  the  point 
where  a  river  debouches  into  the  sea. 


form  its  bed  and  banks.  When  these  materials  cease  to  be  im- 
pelled by  the  force  of  the  moving  water,  they  sink  to  the  bot- 
tom, the  heaviest  pebbles,  of  course,  sinking  first,  the  smaller 


i8  PRINCIPLES  OF  PALEONTOLOGY. 

pebbles  and  sand  next,  and  the  finest  mud  last.  Ultimately, 
therefore,  as  might  have  been  inferred  upon  theoretical  grounds 
and  as  is  proved  by  practical  experience,  every  lake  becomes  a 
receptacle  for  a  series  of  stratified  rocks  produced  by  the  streams 
flowing  into  it.  These  deposits  may  vary  in  different  parts  of 
the  lake,  according  as  one  stream  brought  down  one  kind  of 
material  and  another  stream  contributed  another  material ;  but 
in  all  cases  the  materials  will  bear  ample  evidence  that  they  were 
produced,  sorted,  and  deposited  by  running  water.  The  finer 
beds  of  clay  or  sand  will  all  be  arranged  in  thicker  or  thinner 
layers  or  laminae;  and  if  there  are  any  beds  of  pebbles  these 
will  all  be  rounded  or  smooth,  just  like  the  water-worn  pebbles 
of  any  brook-course.  In  all  probability,  also,  we  should  find  in 
some  of  the  beds  the  remains  of  fresh-water  shells  or  plants  or 
other  organisms  which  inhabited  the  lake  at  the  time  these  beds 
were  being  deposited. 

In  the  same  way  large  rivers — such  as  the  Ganges  or 
Mississippi — deposit  all  the  materials  which  they  bring  down  at 
their  mouths,  forming  in  this  way  their  "  deltas. "  Whenever 
such  a  delta  is  cut  through,  either  by  man  or  by  some  channel  of 
the  river  altering  its  course,  we  find  that  it  is  composed  of  a  suc- 
cession of  horizontal  layers  or  strata  of  sand  or  mud,  varying  in 
mineral  composition,  in  structure,  or  in  grain,  according  to  the 
nature  of  the  material  brought  down  by  the  river  at  different 
periods.  Such  deltas,  also,  will  contain  the  remains  of  animals 
which  inhabit  the  river,  with  fragments  of  the  plants  which 
grew  on  its  banks,  or  bones  of  the  animals  which  lived  in  its 
basin. 

Nor  is  this  action  confined,  of  course,  to  large  rivers  only, 
though  naturally  most  conspicuous  in  the  greatest  bodies  of 
water.  On  the  contrary,  all  streams,  of  whatever  size  are 
engaged  in  the  work  of  wearing  down  the  dry  land,  and  of 
transporting  the  materials  thus  derived  from  higher  to  lower 
levels,  never  resting  in  this  work  till  they  reach  the  sea. 

Lastly,  the  sea  itself — irrespective  of  the  materials  delivered 
into  it  by  rivers — is  constantly  preparing  fresh  stratified  deposits 
by  its  own  action.  Upon  every  coast-line  the  sea  is  constantly 
eating  back  into  the  land  and  reducing  its  component  rocks  to 
form  the  shingle  and  sand  which  we  see  upon  every  shore. 
The  materials  thus  produced  are  not,  however,  lost,  but  are 
ultimately  deposited  elsewhere  in  the  form  of  new  stratified 
accumulations,  in  which  are  buried  the  remains  of  animals 
inhabiting  the  sea  at  the  time. 


THE  FOSSILIFEROUS  ROCKS.  19 

\Yhenever,  then,  we  find  anywhere  in  the  interior  of  the 
land  any  series  of  beds  having  these  characters — composed,  that 
is,  of  distinct  layers,  the  particles  of  which,  both  large  and  small, 
show  distinct  traces  of  the  wearing  action  of  water — whenever 
and  wherever  we  find  such  rocks,  we  are  justified  in  assuming 
that  they  have  been  deposited  by  water  in  the  manner  above 
mentioned.  Either  they  were  laid  down  in  some  former  lake 
by  the  combined  action  of  the  streams  which  flowed  into  it ; 
or  they  were  deposited  at  the  mouth  of  some  ancient  river, 
forming  its  delta ;  or  they  were  laid  down  at  the  bottom  of  the 
ocean.  In  the  first  two  cases,  any  fossils  which  the  beds  might 
contain  would  be  the  remains  of  fresh-water  or  terrestrial  organ- 
isms. In  the  last  case,  the  majority,  at  any  rate,  of  the  fossils 
would  be  the  remains  of  marine  animals. 

The  term  "  formation  "  is  employed  by  geologists  to  express 
"  any  group  of  rocks  which  have  some  character  in  common, 
whether  of  origin,  age,  or  composition "  (Lyell)  ;  so  that  we 
may  speak  of  stratified  and  unstratified  formations,  aqueous 
or  igneous  formations,  fresh-water  or  marine  formations,  and 
so  on. 


CHIEF  DIVISIONS  OF  THE  AQUEOUS  ROCKS. 

The  Aqueous  Rocks  may  be  divided  into  two  great  sections, 
the  Mechanically-formed  and  the  Chemically-formed,  includ- 
ing under  the  last  head  all  rocks  which  owe  their  origin  to 
vital  action,  as  well  as  those  produced  by  ordinary  chemical 
agencies. 

A.  MECHANICALLY-FORMED  ROCKS. — These  are  all  those 
Aqueous  Rocks  of  which  we  can  obtain  proofs  that  their  particles 
have  been  mechanically  transported  to  their  present  situation. 
Thus,  if  we  examine  a  piece  of  conglomerate  or  puddingstone, 
we  find  it  to  be  composed  of  a  number  of  rounded  pebbles  em- 
bedded in  an  enveloping  matrix  or  paste,  which  is  usually  of  a 
sandy  nature,  but  may  be  composed  of  carbonate  of  lime  (when 
the  rock  is  said  to  be  "Calcareous  conglomerate").  The  peb- 
bles in  all  conglomerates  are  worn  and  rounded  by  the  action  of 
water  in  motion,  and  thus  show  that  they  have  been  subjected 
to  much  mechanical  attrition  whilst  they  have  been  mechanically 
transported  for  a  greater  or  less  distance  from  the  rock  of 
which  they  originally  formed  part.  The  analogue  of  the  old  con- 
glomerates at  the  present  day  is  to  be  found  in  the  great  beds 


20  PRINCIPLES  OF  PALEONTOLOGY. 

of  shingle  and  gravel  which  are  formed  by  the  action  of  the  sea 
on  every  coast-line,  and  which  are  composed  of  water-worn  and 
well-rounded  pebbles  of  different  sizes.  A  breccia  is  a  mechan- 
ically-formed rock,  very  similar  to  a  conglomerate,  and  consisting 
of  larger  or  smaller  fragments  of  rock  embedded  in  a  common 
matrix.  The  fragments,  however,  are  in  this  case  all  more  or 
less  angular,  and  are  not  worn  or  rounded.  The  fragments  in 
breccias  may  be  of  large  size,  or  they  may  be  comparatively 
small  (fig.  6)  ;  and  the  matrix  may  be  composed  of  sand  (are- 
naceous) or  of  carbonate  of 
lime  (calcareous).  In  the  case 
of  an  ordinary  sandstone, 
again,  we  have  a  rock  which 
may  be  regarded  as  simply  a 
very  fine-grained  conglomerate 
or  breccia,  being  composed  of 
small  grains  of  sand  (silica), 
sometimes  rounded,  sometimes 
more  or  less  angular,  cemented 
together  by  some  such  sub- 
stance as  oxide  of  iron,  silicate 
of  iron,  or  carbonate  of  lime. 
A  sandstone,  therefore,  like  a  Fig.  6. -Microscopic section  of  a  calcare- 
conglomerate,  is  a  mechanic-  °us  breccia  in  the  Lower  Silurian  (Coniston 
.  Limestone)  of  Snap  Wells,  Westmoreland. 

ally- formed     rock,     Its     COmpO-    The  fragments  are  all  of  small  size,  and 

npnt    o-rainc    hpincr    Pnnallv    thp    consist  of  angular  pieces  of  transparent 

,ing    equally    1     e    quartz,  volcanic  ashes,  and  limestone  em- 

resillt    of    mechanical    attrition    bedded  in  a  matrix  of  crystalline  limestone. 

,  .  (Original.) 

and  having  equally  been  trans- 
ported from  a  distance ;  and  the  same  is  true  of  the  ordinary 
sand  of 'the  sea-shore,  which  is  nothing  more  than  an  uncon- 
solidated  sandstone.  Other  so-called  sands  and  sandstones, 
though  equally  mechanical  in  their  origin,  are  truly  calcareous 
in  their  nature,  and  are  more  or  less  entirely  composed  of 
carbonate  of  lime.  Of  this  kind  are  the  shell-sand  so  common 
on  our  coast?,  and  the  coral-sand  which  is  so  largely  formed  in 
the  neighborhood  of  coral-reefs.  In  these  cases  the  rock  is  com- 
posed of  fragments  of  the  skeletons  of  shell-fish  and  numerous 
other  marine  animals,  together,  in  many  instances,  with  the 
remains  of  certain  sea-weeds  (Corallines,  Nullipores,  &c.)  which 
are  endowed  with  the  power  of  secreting  carbonate  of  lime  from 
the  sea-water.  Lastly,  in  certain  rocks  still  finer  in  their  texture 
than  sandstones,  such  as  the  various  mud-rocks  and  shales,  we 
can  still  recognize  a  mechanical  source  and  origin.  If  slices  of 


THE  FOSSILIFEROUS  ROCKS.  21 

any  of  these  rocks  sufficiently  thin  to  be  transparent  are 
examined  under  the  microscope,  it  will  be  found  that  they  are 
composed  of  minute  grains  of  different  sizes,  which  are  all  more 
or  less  worn  and  rounded,  and  which  clearly  show,  therefore, 
that  they  have  been  subjected  to  mechanical  attrition. 

All  the  above-mentioned  rocks,  then,  are  mechanically-formed 
rocks ;  and  they  are  often  spoken  of  as  "  Derivative  Rocks, " 
in  consequence  of  the  fact  that  their  particles  can  be  shown  to 
have  been  mechanically  derived  from  other  pre-existent  rocks. 
It  follows  from  this  that  every  bed  of  any  mechanically-formed 
rock  is  the  measure  and  equivalent  of  a  corresponding  amount 
of  destruction  of  some  older  rock.  It  is  not  necessary  to  enter 
here  into  a  minute  account  of  the  subdivisions  of  these  rocks, 
but  it  may  be  mentioned  that  they  may  be  divided  into  two 
principal  groups,  according  to  their  chemical  composition.  In  the 
one  group  we  have  the  so-called  Arenaceous  (Lat.  arena,  sand) 
or  Siliceous  Rocks,  which  are  essentially  composed  of  larger  or 
smaller  grains  of  flint  or  silica.  In  this  group  are  comprised 
ordinary  sand,  the  varieties  of  sandstone  and  grit,  and  most 
conglomerates  and  breccias.  We  shall,  however,  afterwards  see 
that  some  siliceous  rocks  are  of  organic  origin.  In  fhe  second  group 
are  the  so-called  Argillaceous  (Lat.  argilla,  clay)  Rocks,  which 
contain  a  larger  or  smaller  amount  of  clay  or  hydrated  silicate  of 
alumina  in  their  composition.  Under  this  head  come  clays, 
shales,  marls,  marl-slate,  clay-slates,  and  most  flags  and  flagstones. 

B.  CHEMICALLY-FORMED  ROCKS. — In  this  section  are  com- 
prised all  those  Aqueous  or  Sedimentary  Rocks  which  have 
been  formed  by  chemical  agencies.  As  many  of  these  chemi- 
cal agencies,  however,  are  exerted  through  the  medium  of  living 
beings,  whether  animals  or  plants,  we  get  into  this  section  a 
number  of  what  may  be  called  "  organically-formed  rocks. " 
These  are  of  the  greatest  possible  importance  to  the  palaeon- 
tologist, as  being  to  a  greater  or  less  extent  composed  of  the 
actual  remains  of  animals  or  vegetables,  and  it  will  therefore  be 
necessary  to  consider  their  character  and  structure  in  some 
detail. 

By  far  the  most  important  of  the  chemically-formed  rocks 
are  the  so-called  Calcareous  Rocks  (Lat.  calx,  lime),  com- 
prising all  those  which  contain  a  large  proportion  of  carbonate  of 
lime,  or  are  wholly  composed  of  this  substance.  Carbonate 
of  lime  is  soluble  in  water  holding  a  certain  amount  of  car- 
bonic acid  gas  in  solution;  and  it  is,  therefore,  found  in  larger 
or  smaller  quantity  dissolved  in  all  natural  waters,  both  fresh 


22  PRINCIPLES  OF  PALAEONTOLOGY. 

and  salt,  since  these  waters  are  always  to  some  extent  charged 
with  the  above-mentioned  solvent  gas.  A  great  number  of 
aquatic  animals,  however,  together  with  some  aquatic  plants, 
are  endowed  with  the  power  of  separating  the  lime  thus  held 
in  solution  in  the  water,  and  of  reducing  it  again  to  its  solid 
condition.  In  this  way  shell-fish,  crustaceans,  sea-urchins,  corals, 
and  an  immense  number  of  other  animals,  are  enabled  to  con- 
struct their  skeletons;  whilst  some  plants  form  hard  structures 
within  their  tissues  in  a  precisely  similar  manner.  We  do  meet 
with  some  calcareous  deposits,  such  as  the  "  stalactites "  and 
"  stalagmites  "  of  caves,  the  "  calcareous  tufa  "  and  "  travertine  " 
of  some  hot  springs,  and  the  spongy  calcareous  deposits  of  so- 
called  "  petrifying  springs, "  which  are  purely  chemical  in  their 
origin,  and  owe  nothing  to  the  operation  of  living  beings.  Such 
deposits  are  formed  simply  by  the  precipitation  of  carbonate  of 
lime  from  water,  in  consequence  of  the  evaporation  from  the 
water  of  the  carbonic  acid  gas  which  formerly  held  the  lime  in 
solution ;  but,  though  sometimes  forming  masses  of  con- 
siderable thickness  and  of  geological  importance,  they  do  not 
concern  us  here.  Almost  all  the  limestones  which  occur  in  the 
series  of  the  stratified  rocks  are,  primarily  at  any  rate,  of  organic 
origin,  and  have  been,  directly  or  indirectly,  produced  by  the 
action  of  certain  lime-making  animals  or  plants,  or  both  combined. 
The  presumption  as  to  all  the  calcareous  rocks,  which  cannot 
be  clearly  shown  to  have  been  otherwise  produced,  is  that  they 
are  thus  organically  formed ;  and  in  many  cases  this  presump- 
tion can  be  readily  reduced  to  a  certainty.  There  are  many 
varieties  of  the  calcareous  rocks,  but  the  following  are  those 
which  are  of  the  greatest  importance : — 

Chalk  is  a  calcareous  rock  of  a  generally  soft  and  pulver- 
ulent texture,  and  with  an  earthy  fracture.  It  varies  in  its 
purity,  being  sometimes  almost  wholly  composed  of  carbonate 
of  lime,  and  at  other  times  more  or  less  intermixed  with  foreign 
matter.  Though  usually  soft  and  readily  reducible  to  powder, 
chalk  is  occasionally,  as  in  the  north  of  Ireland,  tolerably  hard 
and  compact ;  but  it  never  assumes  the  crystalline  aspect  and 
stony  density  of  limestone,  except  it  be  in  immediate  contact  with 
some  mass  of  igneous  rock.  By  means  of  the  microscope,  the 
true  nature  and  mode  of  formation  of  chalk  can  be  determined 
with  the  greatest  ease.  In  the  case  of  the  harder  varieties,  the 
examination  can  be  conducted  by  means  of  slices  ground  down 
to  a  thinness  sufficient  to  render  them  transparent;  but  in  the 
softer  kinds  the  rock  must  be  disintegrated  under  water,  and  the 


THE  FOSSILIFEROUS  ROCKS. 


debris  examined  microscopically.  When  investigated  by  either  of 
these  methods,  chalk  is  found  to  be  a  genuine  organic  rock,  being 
composed  of  the  shells  or  hard  parts  of  innumerable  marine 
animals  of  different  kinds,  some  entire,  some  fragmentary, 
cemented  together  by  a  matrix  of  very  finely  granular  carbonate 
of  lime.  Foremost  amongst  the  animal  remains  which  so  largely 
compose  chalk  are  the  shells  of  the  minute  creatures  which  will  be 
subsequently  spoken  of  under  the  name  of  Foraminifera  (fig.  7), 

and  which,  in  spite  of  their 
microscopic  dimensions,  play  a 
more  important  part  in  the 
process  of  lime-making  than 
perhaps  any  other  of  the  larger 
inhabitants  of  the  ocean. 

As  chalk  is  found  in  beds 
of  hundreds  of  feet  in  thick- 


examined by  transmitted  light  and  highly 
magnified.  Besides  the  entire  shells  of 
Gflobigerina,  Rotalia,  and  Textularia 
of 


ness,  and  of  great  purity,  there 
was  long  felt  much  difficulty 
in  satisfactorily  accounting  for 
its  mode  of  formation  and  ori- 
gin. By  the  researches  of 
Carpenter,  Wyville  Thomson, 
Fig.  7.-Section  of  Gravesend  Chalk,  Huxley,  Wallich,  and  others, 

it     has,     however,     been     shown 

.  .... 

that    there    IS    now    forming,    in 

<he  pr°f°und  ******  ™ 

great  oceans,  a  deposit  which 
is  in  all  essential  respects  identical  with  chalk,  and  which  is 
generally  known  as  the  "  Atlantic  ooz, "  from  its  having  been 
first  discovered  in  that  sea.  This  ooze  is  found  at  great 
depths  (5000  to  over  15,000  feet)  in  both  the  Atlantic  and 
Pacific,  covering  enormously  large  areas  of  the  sea-bottom, 
and  it  presents  itself  as  a  whitish-brown,  sticky,  impalpable  mud, 
very  like,  greyish  chalk  when  dried.  Chemical  examination 
shows  that  the  ooze  is  composed  almost  wholly  of  carbonate  of 
lime,  and  microscopical  examination  proves  it  to  be  of  organic 
origin,  and  to  be  made  up  of  the  remains  of  living  beings. 
The  principal  forms  of  these  belong  to  the  Foraminifera,  and 
the  commonest  of  these  are  the  irregularly-chambered  shells  of 
Globigcrina,  absolutely  indistinguishable  from  the  Globigerina: 
which  are  so  largely  present  in  the  chalk  (fig.  8).  Along  with 
these  occur  fragments  of  the  skeletons  of  other  larger  creatures, 
and  a  certain  proportion  of  the  flinty  cases  of  minute  animal  and 


PRINCIPLES  OF  PALAEONTOLOGY. 


vegetable  organisms  (Polycystina  and  Diatoms).  Though  many 
of  the  minute  animals,  the 
hard  parts  of  which  form  the 
ooze,  undoubtedly  live  at  or 
near  the  surface  of  the  sea, 
others,  probably,  really  live 
near  the  bottom;  and  the  ooze 
itself  forms  a  congenial  home 
for  numerous  sponges,  sea- 
lilies,  and  other  marine  ani- 
mals which  flourish  at  great 
depths  in  the  sea.  There  is 
thus  established  an  intimate 
and  most  interesting  parallel- 
ism between  the  chalk  and 
the  ooze  of  modern  oceans. 


Fig.  8.— Organisms  in  the  Atlantic  Ooze, 
chiefly     Foraminlfera    (Globigerinn    and 


Both  are  formed  essentially  in  Textularia),  with  1  >olycystina  and  sponge- 
the  same  way,  and  the  latter  ^ules;  highly  magnified.  (Original.) 

only  requires  consolidation  to  become  actually  converted  into 
chalk.  Both  are  fundamentally  organic  deposits,  apparently 
requiring  a  great  depth  of  water  for  their  accumulation,  and 
mainly  composed  of  the  remains  of  Foraminifera,  together  with 
the  entire  or  broken  skeletons  of  other  marine  animals  of  greater 
dimensions.  It  is  to  be  remembered,  however,  that  the  ooze, 
though  strictly  representative  of  the  chalk,  cannot  be  said  in  any 
proper  sense  to  be  actuall}'  identical  with  the  formation  so  called 
by  geologists.  A  great  lapse  of  time  separates  the  two,  and 
though  composed  of  the  remains  of  representative  classes  or 
groups  of  animals,  it  is  only  in  the  case  of  the  lowly-organized 
Globigerina,  and  of  some  other  organisms  of  little  higher  grade, 
that  we  find  absolutely  the  same  kinds  or  species  of  animals  in 
both. 

Limestone,  like  chalk,  is  composed  of  carbonate  of  lime, 
sometimes  almost  pure,  but  more  commonly  with  a  greater  or 
less  intermixture  of  some  foreign  material,  such  as  alumina  or 
silica.  The  varieties  of  limestone  are  almost  innumerable,  but 
the  great  majority  can  be  clearly  proved  to  agree  with  chalk  in 
being  essentially  of  organic  origin,  and  in  being  more  or  less 
largely  composed  of  the  remains  of  living  beings.  In  many 
instances  the  organic  remains  which  compose  limestone  are  so 
large  as  to  be  readily  visible  to  the  naked  eye,  and  the  rock  is 
at  once  seen  to  be  nothing  more  than  an  agglomeration  of  the 
skeletons,  generally  fragmentary,  of  certain  marine  animals, 


THE  FOSSILIFEROUS  ROCKS.  25 

cemented  together  by  matrix  of  carbonate  of  lime.  This  is  the 
case,  for  example,  with  the  so-called  "  Crinoidal  Limestones " 
and  "  Encrinital  Marbles  "  with  which  the  geologist  is  so  familiar, 
especially  as  occurring  in  great  beds  amongst  the  older  for- 
mations of  the  earth's  crust.  These  are  seen,  on  weathered  or 
broken  surfaces,  or  still  better  in  polished  slabs  (fig.  9),  to  be  com- 


Fig.  9.— Slab  of  Crinoidal  marble,  from  the  Carboniferous  limestone  of  Dent, In 
Yorkshire,  of  the  natural  size.  The  polished  surface  intersects  the  columns  of  the 
Crinolds  at  different  angles,  and  thus  gives  rise  to  varying  appearances.  (Original.) 

posed  more  or  less  exclusively  of  the  broken  stems  and  detached 
plates  of  sea-lilies  (Crinoids).  Similarly,  other  limestones  are 
composed  almost  entirely  of  the  skeletons  of  corals ;  and  such 
old  coralline  limestones  can  readily  be  paralleled  by  formations 
which  we  can  find  in  actual  course  of  production  at  the  present 
day.  We  only  need  to  transport  ourselves  to  the  islands  of  the 
Pacific,  to  the  West  Indies,  or  to  the  Indian  Ocean,  to  find  great 
masses  of  lime  formed  similarly  by  living  corals,  and  well  known 
to  every  one  under  the  name  of  "  coral-reefs.  "  Such  reefs  are 
often  of  vast  extent,  both  superficially  and  in  vertical  thickness, 
and  they  fully  equal  in  this  respect  any  of  the  coralline  lime- 
stones of  bygone  ages.  Again,  we  find  other  limestones — such 
as  the  celebrated  "  Nummulitic  Limestone"  (fig.  10),  which 
sometimes  attains  a  thickness  of  some  thousands  of  feet — which 
are  almost  entirely  made  up  of  the  shells  of  Foraminifera.  In 
the  case  of  the  "Nummulitic  Limestone,"  just  mentioned,  these 


26  PRINCIPLES  OF  PALEONTOLOGY. 

shells  are  of  a  large  size,  varying  from  the  size  of  a  split  pea  up 
to  that  of  a  florin.  There  are,  however,  as  we  shall  see,  many 
other  limestones,  which  are  likewise  largely  made  up  of 


Fig.  10. — Piece  of  Nummulitlc  Limestone  from  the  Great  Pyramid. 
Of  the  natural  size.    (Original.) 

Foraminifera,  but  in  which  the  shells  are  very  much  more  minute, 
and  would  hardly  be  seen  at  all  without  the  microscope. 

We  may,  in  fact,  consider  that  the  great  agents  in  the  pro- 
duction of  limestones  in  past  ages  have  been  animals  belonging 
to  the  Crinoids,  the  Corals,  and  the  Foraminifera.  At  the  pres- 
ent day,  the  Crinoids  have  been  nearly  extinguished,  and  the 
few  known  survivors  seem  to  have  retired  to  great  depths  in  the 
ocean;  but  the  two  latter  still  actively  carry  on  the  work  of 
lime-making,  the  former  being  very  largely  helped  in  their 
operations  by  certain  lime-producing  marine  plants  (Nullipores 
and  Corallines}.  We  have  to  remember,  however,  that  though 
the  limestones,  both  ancient  and  modern,  that  we  have  just 
spoken  of,  are  truly  organic,  they  are  not  necessarily  formed  out 
of  the  remains  of  animals  which  actually  lived  on  the  precise 
spot  where  we  now  find  the  limestone  itself.  WTe  may  find  a 
crinoidal  limestone,  which  we  can  show  to  have  been  actually 
formed  by  the  successive  growth  of  generations  of  sea-lilies  in 
place;  but  we  shall  find  many  others  in  which  the  rock  is  made 
up  of  innumerable  fragments  of  the  skeletons  of  these  creatures, 
which  have  been  clearly  worn  and  rubbed  by  the  sea-waves,  and 
which  have  been  mechanically  transported  to  their  present  site. 


THE  FOSSILIFEROUS  ROCKS.  27 

In  the  same  way,  a  limestone  may  be  shown  to  have  been  an 
actual  coral-reef,  by  the  fact  that  we  find  in  it  great  masses  of 
coral,  growing  in  their  natural  position,  and  exhibiting  plain 
proofs  that  they  were  simply  quietly  buried  by  the  calcareous 
sediment  as  they  grew ;  but  other  limestones  may  contain  only 
numerous  rolled  and  water-worn  fragments  of  corals.  This  is 
precisely  paralleled  by  what  we  can  observe  in  our  existing 
coral-reefs.  Parts  of  the  modern  coral-islands  and  coral-reefs 
are  really  made  up  of  corals,  dead  or  alive,  which  actually  grew 
on  the  spot  where  we  now  find  them;  but  other  parts  are  com- 
posed of  limestone-rock  ("coral-rock"),  or  of  a  loose  and 
("coral-sand"),  which  is  organic  in  the  sense  that  it  is  com- 
posed of  lime  formed  by  living  beings,  but  which,  in  truth,  is 
composed  or  fragments  of  the  skeletons  of  these  living  beings, 
mechanically  transported  and  heaped  together  by  the  sea.  To 
take  another  example  nearer  home,  we  may  find  great  accumu- 
lations of  calcareous  matter  formed  in  place,  by  the  growth  of 
shell-fish,  such  as  oysters  or  mussels ;  but  we  can  also  find 
equally  great  accumulations  on  many  of  our  shores  in  the  form 
of  "  shell-sand  "  which  is  equally  composed  of  the  shells  of  mol- 
luscs, but  which  is  formed  by  the  trituration  of  these  shells  by 
the  mechanical  power  of  the  sea-waves.  We  thus  see  that  though 
all  these  limestones  are  primarily  organic,  they  not  uncommonly 
become  "  mechanically-formed "  rocks  in  a  secondary  sense,  the 
materials  of  which  they  are  composed  being  formed  by  living 
beings,  but  having  been  mechanically  transported  to  the  place 
where  we  now  find  them. 

Many  limestones,  as  we  have  seen,  are  composed  of  large 
and  conspicuous  organic  remains,  such  as  strike  the  eye  at  once. 
Many  others,  however,  which  at  first  sight  appear  compact,  more 
or  less  crystalline,  and  nearly  devoid  of  traces  of  life,  are  found, 
when  properly  examined,  to  be  also  composed  of  the  remains  of 
various  organisms.  All  the  commoner  limestones,  in  fact  from 
the  Lower  Silurian  period  onwards,  can  be  easily  proved  to 
be  thus  organic  rocks,  if  we  investigate  weathered  or  polished  sur- 
faces with  a  lens,  or,  still  better,  if  we  cut  thin  slices  of  the  rock 
and  grind  these  down  till  they  are  transparent.  When  thus  ex- 
amined, the  rock  is  usually  found  to  be  composed  of  innumerable 
entire  or  fragmentary  fossils,  cemented  together  by  a  granular 
or  crystalline  matrix  of  carbonate  of  lime  (figs.  II  and  12). 
When  the  matrix  is  granular,  the  rock  is  precisely  similar  to 
chalk,  except  that  it  is  harder  and  less  earthy  in  texture,  whilst 
the  fossils  are  only  occasionally  referable  to  the  Foraminifera. 


28 


PRINCIPLES  OF  PALEONTOLOGY, 


In  other  cases,  the  matrix  is  more  or  less  crystalline,  and  when 
this  crystallization  has  been  carried  to  a  great  extent,  the  original 
organic  nature  of  the  rock  may  be  greatly  or  completely  obscured 
thereby.  Thus,  in  limestones  which  have  been  greatly  altered 
or  "  metamorphosed "  by  the  combined  action  of  heat  and  pres- 


Fig.  11. —  Section  of  Carboniferous 
Limestone  from  Spergen  Hill,  Indiana, 
U.  S.,  showing  numerous  large-sized 
Foraminifera  (Endothyra)  and  a  few 
oolitic  grains  ;  magnified.  (Original.) 


Fig.12.— Section  of  Ccniston  Limestone 
(Lower  Silurian)  from  Keisley,  West- 
moreland; magnified.  The  matrix  is 
very  coarsely  crystalline,  and  the  in- 
cluded organic  remains  are  chiefly  stems 
of  Crinoids.  (Original.) 


sure,  all  traces  of  organic  remains  become  annihilated,  and  the 
rock  becomes  completely  crystalline  throughout.  This,  for 
example,  is  the  case  with  the  ordinary  white  "  statuary  marble, " 
slices  of  which  exhibit  under  the  microscope  nothing  but  an 
aggregate  of  beautifully  transparent  crystals  of  carbonate  of 
lime,  without  the  smallest  traces  of  fossils.  There  are  also  other 
cases,  where  the  limestone  is  not  necessarily  high  crystalline, 
and  where  no  metamorphic  action  in  the  strict  sense  has  taken 
place,  in  which,  nevertheless,  the  microscope  fails  to  reveal  any 
evidence  that  the  rock  is  organic.  Such  cases  are  somewhat 
obscure,  and  doubtless  depend  on  different  causes  in  different 
instances ;  but  they  do  not  affect  the  important  generalization 
that  limestones  are  fundamentally  the  product  of  the  operation 
of  living  beings.  This  fact  remains  certain;  and  when  we  con- 
sider the  vast  superficial  extent  occupied  by  calcareous  deposits, 
and  the  enormous  collective  thickness  of  these,  the  mind  cannot 
fail  to  be  impressed  with  the  immensity  of  the  period  demanded 
for  the  formation  of  these  by  the  agency  of  such  humble  and 
often  microscopic  creatures  as  Corals,  Sea-lilies,  Foraminifers, 
and  Shell-fish. 


THE  FOSSILIFEROUS  ROCKS.  29 

Amongst  the  numerous  varieties  of  limestone,  a  few  are  of 
such  interest  as  to  deserve  a  brief  notice.  Magnesia  limestone 
or  dolomite,  differs  from  ordinary  limestone  in  containing  a  cer- 
tain proportion  of  carbonate  of  magnesia  along  with  the  carbon- 
ate of  lime.  The  typical  dolomites  contain  a  large  proportion  of 
carbonate  of  magnesia,  and  are  highly  crystalline.  The  ordi- 
nary magnesian  limestones  (such  as  those  of  Durham  in  the 
Permian  series,  and  the  Guelph  Limestones  of  North  America 
in  the  Silurian  series)  are  generally  of  a  yellowish,  buff,  or 
brown  color,  with  a  crystalline  or  pearly  aspect,  effervescing 
with  acid  much  less  freely  than  ordinary  limestone,  exhibiting 
numerous  cavities  from  which  fossils  have  been  dissolved  out, 
and  often  assuming  the  most  varied  and  singular  forms  in  con- 
sequence of  what  is  called  "  concretionary  action.  "  Examination 
with  the  microscope  shows  that  these  limestones  are  composed 
of  an  aggregate  of  minute  but  perfectly  distinct  crystals,  but  that 
minute  organisms  of  different  kinds,  or  fragments  of  larger 
fossils,  are  often  present  as  well.  Other  magnesian  limestones, 
again,  exhibit  no  striking  external  peculiarities  by  which  the 
presence  of  magnesia  would  be  readily  recognized,  and  though 
the  base  of  the  rock  is  crystalline,  they  are  replete  with  the 
remains  of  organized  beings.  Thus  many  of  the  magnesian 
limestones  of  the  Carboniferous  series  of  the  North  of  Eng- 
land are  very  like  ordinary  limestone  to  look  at,  through 
effervescing  less  freely  with  acids,  and  the  microscope  proves 
them  to  be  charged  with  remains  of  Foraminifera  and  other 
minute  organisms, 

Marbles  are  of  various  kinds,  all  limestones  which  are  suffi- 
ciently hard  and  compact  to  take  a  high  polish  going  by  this 
name.  Statuary  marble,  and  most  of  the  celebrated  foreign 
marbles,  are  "  metamorphic "  rocks,  of  a  highly  crystalline 
nature,  and  having  all  traces  of  their  primitive  organic  struc- 
ture obliterated.  Many  other  marbles,  however,  differ  from 
ordinary  limestone  simply  in  the  matter  of  density.  Thus, 
many  marbles  (such  as  Derbyshire  marble)  are  simply  "  cri- 
noidal  limestones "  (fig.  9)  ;  whilst  various  other  British 
marbles  exhibit  innumerable  organic  remains  under  the  mi- 
croscope. Black  marbles  owe  their  color  to  the  presence  of 
very  minute  particles  of  carbonaceous  matter,  in  some  cases 
at  any  rate ;  and  they  may  either  be  metamorphic,  or  they  may 
be  charged  with  minute  fossils  such  as  Foraminifera  (e.g.,  the 
black  limestones  of  Ireland,  and  the  black  marble  of  Dent,  in 
Yorkshire). 


PRINCIPLES  OF  PALEONTOLOGY. 


"  Oolitic  "  limestones,  or  "  oolites,  "  as  they  are  often  called, 
are  of  interest  both  to  the  palaeontologist  and  geologist.  The 
peculiar  structure  to  which  they  owe  their  name  is  that  the  rock 
is  more  or  less  entirely  composed  of  spheroidal  or  oval  grains, 
which  vary  in  size  from  the  head  of  a  small  pin  or  less  up  to  the 
size  of  a  pea,  and  which  may  be  in  almost  immediate  contact  with 
one  another,  or  may  be  cemented  together  by  a  more  or  less 
abundant  calcareous  matrix.  When  the  grains  are  pretty  nearly 
spherical  and  are  in  tolerably  close  contact,  the  rock  looks  very 
like  the  roe  of  a  fish,  and  the  name  of  "  oolite  "  or  '  egg-stone  " 
is  in  allusion  to  this.  When  the  grains  are  of  the  size  of  peas  or 
upwards,  the  rock  is  often  called  a  "pisolite"  (Lat.  pisum,  a 
pea).  Limestones  having  this  peculiar  structure  are  especially 
abundant  in  the  Jurassic  formation,  which  is  often  called  the 
"  Oolitic  series  "  for  this  reason  ;  but  essentially  similar  lime- 
stones occur  not  uncommonly  in  the  Silurian,  Devonian,  and 
Carboniferous  formations,  and,  indeed,  in  almost  all  rock  groups 
in  which  limestones  are  largely  developed.  Whatever  may  be 
the  age  of  the  formation  in  which  they  occur,  and  whatever 
may  be  the  size  of  their  component  "  eggs,  "  the  structure  of 
oolitic  limestones  is  fundamentally  the  same.  All  the  ordinary 
oolitic  limestones,  namely,  consist  of  little  spherical  or  ovoid 
"  concretions,  "  as  they  are  termed,  cemented  together  by  a  larger 
or  smaller  amount  of  crystalline  carbonate  of  lime,  together,  in 
many  instances,  with  numerous  organic  remains  of  different 
kinds  (fig.  13).  When  examined  in  polished  slabs,  or  in  thin  sec- 
tions prepared  for  the  micro- 
scope, each  of  these  little  con- 
cretions is  seen  to  consist  of 
numerous  concentric  coats  of 
carbonate  of  lime,  which  some- 
times simply  surround  an  imag- 
inary center,  but  which,  more 
commonly,  have  been  suc- 
cessively deposited  round 
some  foreign  body,  such  as  a 
little  crystal  of  quartz,  a  clus- 
ter of  sand-grains,  or  a  minute 
shell.  In  other  cases,  as  in 
some  of  the  beds  of  the  Car- 
boniferous  limestone  in  the 
North  of  England,  where  the 
limestone  is  highly  "  arenaceous,  "  there  is  a  modification  of  the 


mg    i3.-siice  of   oolitic    limestone 
°' 


THE  FOSSILIFEROUS  ROCKS. 


oolitic  structure.  Microscopic  sections  of  these  sandy  lime- 
stones (fig.  14)  show  numerous  generally  angular  or  oval  grains 
of  silica  or  flint,  each  of  which  is  commonly  surrounded  by  a 
thin  coating  of  carbonate  of  lime,  or  sometimes  by  several  such 
coats,  the  whole  being  cemented  together  along  with  the  shells 
of  Foraminifera  and  other  minute  fossils  by  a  matrix  of  crystal- 
line calcite.  As  compared  with  typical  oolites,  the  concretions 
in  these  limestones  are  usually  much  more  irregular  in  shape, 
often  lengthened  out  and  almost  cylindrical,  at  other  times 
angular,  the  central  nucleus  being  of  large  size,  and  the  sur- 
rounding envelope  of  lime  be- 
ing very  thin,  and  often  exhib- 
iting no  concentric  structure. 
In  both  these  and  the  ordinary 
oolites,  the  structure  is  funda- 
mentally the  same.  Both  have 
been  formed  in  a  sea,  probably 
of  no  great  depth,  the  waters 
of  which  were  charged  with 
carbonate  of  lime  in  solution, 
whilst  the  bottom  was  formed 
of  sand  intermixed  with  min- 
ute shells  and  fragments  of 
the  skeletons  of  larger  marine 
animals.  The  excess  of  lime  in 
the  sea-water  was  precipitated 
round  the  sand-grains,  or  round 
the  smaller  shells,  as  so  many 

nuclei,  and  this  precipitation  must  often  have  taken  place  time 
after  time,  so  as  to  give  rise  to  the  concentric  structure  so  char- 
acteristic of  oolitic  concretions.  Finally,  the  oolitic  grains  thus 
produced  were  cemented  together  by  a  further  precipitation  of 
crystalline  carbonate  of  lime  from  the  waters  of  the  ocean. 

Phosphate  of  Lime  is  another  lime-salt,  which  is  of  interest 
to  the  palaeontologist.  It  does  not  occur  largely  in  the  strati- 
fied series,  but  it  is  found  in  considerable  beds  *  in  the 
Laurentian  formation,  and  less  abundantly  in  some  later  rock- 

*  Apart  from  the  occurrence  of  phosphate  of  lime  in  actual  beds  in  the 
stratified  rocks,  as  in  the  Laurentian  and  Silurian  series,  this  salt  may 
also  occur  disseminated  through  the  rock,  when  it  can  only  be  detected  by 
chemical  analysis.  It  is  interesting  to  note  that  Dr.  Hicks  has  recently 
proved  the  occurrence  of  phosphate  of  lime  in  this  disseminated  form  in 
rocks  as  old  as  the  Cambrian,  and  that  in  quantity  quite  equal  to  what 
is  generally  found  to  be  present  in  the  later  fossiliferous  rocks.  This 
affords  a  chemical  proof  that  animal  life  flourished  abundantly  in  the 
Cambrian  seas. 


Fig.  14. —  Slice  of  arenaceous  and 
oolitic  limestone  from  the  Carbonifer- 
ous series  of  Shap,  Westmoreland;  mag- 
nified. The  section  also  exhibits  Fora- 
minifera and  other  minute  fossils.  (Orig- 
inal.) 


32  PRINCIPLES  OF  PALEONTOLOGY. 

groups,  whilst  it  occurs  abundantly  in  the  form  of  nodules  in 
parts  of  the  Cretaceous  (Upper  Greensand)  and  Tertiary  deposits. 
Phosphate  of  lime  forms  the  larger  proportion  of  the  earthy 
matters  of  the  bones  of  Vertebrate  animals,  and  also  occurs  in 
less  amount  in  the  skeletons  of  certain  of  the  Invertebrates  (e.g., 
Crustacce}.  It  is,  indeed,  perhaps  more  distinctively  than 
carbonate  of  lime,  an  organic  compound ;  and  though  the  for- 
.mation  of  many  known  deposits  of  phosphate  of  lime  cannot  be 
positively  shown  to  be  connected  with  the  previous  operation  of 
living  beings,  there  is  room  for  doubt  whether  this  salt  is  not 
in  reality  always  primarily  a  product  of  vital  action.  The  phos- 
phatic  nodules  of  the  Upper  Greensand  are  erroneously  called 
"  coprolites, "  from  the  belief  originally  entertained  that  they 
were  the  droppings  or  fossilized  excrements  of  extinct  animals; 
and  though  this  is  not  the  case,  there  can  be  little  doubt  but 
that  the  phosphate  of  lime  which  they  contain  is  in  this  instance 
of  organic  origin.  *  It  appears,  in  fact,  that  decaying  animal 
matter  has  a  singular  power  of  determining  the  precipitation 
around  it  of  mineral  salts  dissolved  in  water.  Thus,  when  any 
animal  bodies  are  undergoing  decay  at  the  bottom  of  the  sea, 
they  have  a  tendency  to  cause  the  precipitation  from  the  sur- 
rounding wa-ter  of  any  mineral  matter  which  may  be  dissolved  in 
it ;  and  the  organic  body  thus  becomes  a  center  round  which  the 
mineral  matters  in  question  are  deposited  in  the  form  of  a 
"concretion"  or  "nodule.."  The  phosphatic  nodules  in  question 
were  formed  in  a  sea  in  which  phosphate  of  lime,  derived  from 
the  destruction  of  animal  skeletons,  was  held  largely  in  solution ; 
and  a  precipitation  of  it  took  place  round  any  body,  such  as  a 
decaying  animal  substance,  which  happened  to  be  lying  on  the 
sea-bottom,  and  which  offered  itself  as  a  favorable  nucleus.  In 
the  same  way  we  may  explain  the  formation  of  the  calcareous 
nodules,  known  as  "  septaria  "  or  "  cement  stones, "  which  occur 
so  commonly  in  the  London  Clay  and  Kimmeridge  Clay,  and  in 
which  the  principal  ingredient  is  carbonate  of  lime.  A  similar 
origin  is  to  be  ascribed  to  the  nodules  of  clay  iron-stone  (im- 
pure carbonate  of  iron)  which  occur  so  abundantly  in  the  shales 
of  the  Carboniferous  series  and  in  other  argillaceous  deposits; 
and  a  parallel  modern  example  is  to  be  found  in  the  nodules  of 

*  It  has  been  maintained,  indeed,  that  the  phosphatic  nodules  so 
largely  worked  for  agricultural  purposes,  are  in  themselves  actual  organic 
bodies  or  true  fossils.  In  a  few  cases  this  admits  of  demonstration,  as  it 
can  be  shown  that  the  nodule  is  simply  an  organism  (such  as  a  sponge) 
infiltrated  with  phosphate  of  lime  (Sollas)  ;  but  there  are  many  other  cases 
in  which  no  actual  structure  has  yet  been  shown  to  exist,  and  as  to  the 
true  origin  of  which  it  would  be  hazardous  to  offer  a  positive  opinion. 


THE  FOSSILIFEROUS  ROCKS.  33 

manganese,  which  were  found  by  Sir  Wyville  Thomson,  in  the 
Challenger,  to  be  so  numerously  scattered  over  the  floor  of  the 
Pacific  at  great  depths.  In  accordance  with  this  mode  of 
origin,  it  is  exceedingly  common  to  find  in  the  center  of  all  these 
nodules,  both  old  and  new,  some  organic  body,  such  as  a  bone, 
a  shell,  or  a  tooth,  which  acted  as  the  original  nucleus  of  pre- 
cipitation, and  was  thus  preserved  in  a  shroud  of  mineral  matter. 
Many  nodules,  it  is  true,  show  no  such  nucleus ;  but  it  has  been 
affirmed  that  all  of  them  can  be  shown,  by  appropriate  micro- 
scopical investigation,  to  have  been  formed  round  an  original 
organic  body  to  begin  with  (Hawkins  Johnson). 

The  last  lime-salt  which  need  be  mentioned  is  gypsum,  or 
sulphate  of  lime.  This  substance,  apart  from  the  other  modes 
of  occurrence,  is  not  uncommonly  found  interstratified  with  the 
ordinary  sedimentary  rocks,  in  the  form  of  more  or  less  irregu- 
lar beds ;  and  in  these  cases  it  has  a  palaeontological  importance, 
as  occasionally  yielding  well-preserved  fossils.  Whilst  its  exact 
mode  of  origin  is  uncertain,  it  cannot  be  regarded  as  in  itself  an 
organic  rock,  though  clearly  the  product  of  chemical  action.  To 
look  at,  it  is  usually  a  whitish  or  yellowish-white  rock,  as  coarsely 
crystalline  as  loaf-sugar,  or  more  so;  and  the  microscope  shows 
it  to  be  composed  entirely  of  crystals  of  sulphate  of  lime. 

We  have  seen  that  the  calcareous  or  lime-containing  rocks 
are  the  most  important  of  the  group  of  organic  deposits ;  whilst 
the  siliceous  or  flint-containing  rocks  may  be  regarded  as  the 
most  important,  most  typical  and  most  generally  distributed  of 
the  mechanically-formed  rocks.  We  have,  however,  now  briefly 
to  consider  certain  deposits  which  are  more  or  less  completely 
formed  of  flint ;  which,  nevertheless,  are  essentially  organic  in 
their  origin. 

Flint  or  silex,  hard  and  intractable  as  it  is,  is  nevertheless 
capable  of  solution  in  water  to  a  certain  extent,  and  even  of 
assuming,  under  certain  circumstances,  a  gelatinous  or  viscous 
condition.  Hence,  some  hot-springs  are  impregnated  with  silica 
to  a  considerable  extent ;  it  is  present  in  small  quantity  in  sea- 
water;  and  there  is  reason  to  believe  that  a  minute  proportion 
must  very  generally  be  present  in  all  bodies  of  fresh  water  as 
well.  It  is  from  this  silica  dissolved  in-  the  water  that  many 
animals  and  some  plants  are  enabled  to  construct  for  themselves 
flinty  skeletons;  and  we  find  that  these  animals  and  plants  are 
and  have  been  sufficiently  numerous  to  give  rise  to  very  consider- 
able deposits  of  siliceous  matter  by  the  mere  accumulation  of 
their  skeletons.  Amongst  the  animals  which  require  special 
3 


34 


PRINCIPLES  OF  PALEONTOLOGY. 


mention  in  this  connection  are  the  microscopic  organisms  which 
are  known  to  the  naturalist  as  Polycystina.  These  little  creatures 
are  the  lowest  possible  grade  of  organization,  very  closely 
related  to  the  animals  which  we  have  previously  spoken  of  as 
Foraminifera,  but  differing  in  the  fact  that  they  secrete  a  shell 
or  skeleton  composed  of  flint  instead  of  lime.  The  Polycystina 
occur  abundantly  in  our  present  seas ;  and  their  shells  are  present 
in  some  numbers  in  the  ooze  which  is  found  at  great  depths  in 
the  Atlantic  and  Pacific  oceans,  being  easily  recognized  by  their 
exquisite  shape,  their  glassy  transparency,  the  general  presence 
of  longer  or  shorter  spines,  and  the  sieve-like  perforations  in 
the  walls.  Both  in  Barbadoes  and  in  the  Nicobar  islands  occur 
geological  formations  which  are  composed  of  the  flinty  skeletons 
of  these  microscopic  animals;  the  deposit  in  the  former  locality 
attaining  a  great  thickness,  and  having  been  long  known  to 
workers  with  the  microscope  under  the  name  of  "  Barbadoes 
earth"  (fig.  15). 


Fig.  15.  —  Shells  of  Polycyatina  from 
•'•Barbadoes  earth ;"  greatly  magnified. 
(Original.) 


Fig.  16.— Cases  of  Diatoms  in  the  Rich- 
mond  "Infusorial  earth  ;"  highly  magni- 
fied. (Original.) 


In  addition  to  flint-producing  animals,  we  have  also  the  great 
group  of  fresh-water  and  marine  microscopic  plants  known  as 
Diatoms,  which  likewise  secrete  a  siliceous  skeleton,  often  of 
great  beauty.  The  skeletons  of  Diatoms  are  found  abundantly 
at  the  present  day  in  lake-deposits,  guano,  the  silt  of  estuaries, 
and  in  mud  which  covers  many  parts  of  the  sea-bottom;  they 
have  been  detected  in  strata  of  great  age;  and  in  spite  of  their 
microscopic  dimensions,  they  have  not  uncommonly  accumulated 
to  form  deposits  of  great  thickness,  and  of  considerable  super- 
ficial extent.  Thus  the  celebrated  deposit  of  "  tripoli "  ("  Polir- 


THE  FOSSILIFEROUS  ROCKS.  35 

schiefer")  of  Bohemia,  largely  worked  as  polishing-powder,  is 
composed  wholly,  or  almost  wholly,  of  the  flinty  cases  of  Diatoms, 
of  which  it  is  calculated  that  no  less  than  forty-one  thousand 
millions  go  to  make  up  a  single  cubic  inch  of  the  stone.  Another 
celebrated  deposit  is  the  so-called  "  Infusorial  earth "  of  Rich- 
mond in  Virginia,  where  there  is  a  stratum  in  places  thirty  feet 
thick,  composed  almost  entirely  of  the  microscopic  shells  of 
Diatoms. 

Nodules  or  layers  of  flint,  or  the  impure  variety  of  flint 
known  as  chert,  are  found  in  limestones  of  almost  all  ages  from 
the  Silurian  upwards;  but  they  are  especially  abundant  in  the 
chalk.  When  these  flints  are  examined  in  thin  and  transparent 
slices  under  the  microscope,  or  in  polished  sections,  they  are 
found  to  contain  an  abundance  of  minute  organic  bodies — such 
as  Foraminifera,  sponge-spicules,  &c. — embedded  in  a  siliceous 
basis.  In  many  instances  the  flint  contains  larger  organisms — 
such  as  a  Sponge  or  Sea-urchin.  As  the  flint  has  completely 
surrounded  and  infiltrated  the  fossils  which  it  contains,  it  is 
obvious  that  it  must  have  been  deposited  from  sea-water  in  a 
gelatinous  condition,  and  subsequently  have  hardened.  N  That 
silica  is  capable  of  assuming  this  viscous  and  soluble  condition 
is  known;  and  the  formation  of  flint  may  therefore  be  regarded 
as  due  to  the  separation  of  silica  from  the  sea-water  and  its 
deposition  round  some  organic  body  in  a  state  of  chemical 
change  or  decay,  just  as  nodules  of  phosphate  of  lime  or  carbon- 
ate of  iron  are  produced.  The  existence  of  numerous  organic 
bodies  in  flint  has  long  been  known ;  but  it  should  be  added  that 
a  recent  observer  (Mr.  Hawkins  Johnson)  asserts  that  the 
existence  of  an  organic  structure  can  be  demonstrated  by  suit- 
able methods  of  treatment,  even  in  the  actual  matrix  or  basis  of 
the  flint.  * 

In  addition  to  the  deposits  formed  of  flint  itself,  there  are 
other  siliceous  deposits  formed  by  certain  silicates,  and  also  of 
organic  origin.  It  has  been  shown,  namely — by  observations 
carried  out  in  our  present  seas — that  the  shells  of  Foraminifera 
are  liable  to  become  completely  infiltrated  by  silicates  (such  as 
"  glauconite,  "  or  silicate  of  iron  and  potash).  Should  the  actual 
calcareous  shell  become  dissolved  away  subsequent  to  this  infil- 
tration—as is  also  liable  to  occur — then,  in  place  of  the  shells  of 

*  It  has  been  asserted  that  the  flints  of  the  chalk  are  merely  fossil 
sponges.  No  explanation  of  the  origin  of  flint,  however,  can  be  satisfac- 
tory, unless  it  embraces  the  origin  of  chert  in  almost  all  great  limestones 
from  the  Silurian  upwards,  as  well  as  the  common  phenomenon  of  the 
silincation  of  organic  bodies  (such  as  corals  and  shells)  which  are  known 
with  certainty  to  have  been  originally  calcareous. 


36  PRINCIPLES  OF  PALEONTOLOGY. 

the  Foraminifera,  we  get  a  corresponding  number  of  green  sandy 
grains  of  glauconite.,  each  grain  being  the  cast  of  a  single  shell. 
It  has  thus  been  shown  that  the  green  sand  found  covering  the 
sea-bottom  in  certain  localities  (as  found  by  the  Challenger 
expedition  along  the  line  of  the  Agulhas  current)  is  really 
organic,  and  is  composed  of  casts  of  the  shells  of  Foraminifera. 
Long  before  these  observations  had  been  made,  it  had  been  shown 
by  Professor  Ehrenberg  that  the  green  sands  of  various  geologi- 
cal formations  are  composed  mainly  of  the  internal  casts  of  the 
shells  of  Foraminifera;  and  we  have  thus  another  and  a  very 
interesting  example  how  rock-deposits  of  considerable  extent  and 
of  geological  importance  can  be  built  up  by  the  operation  of  the 
minutest  living  beings. 

As  regards  argillaceous  deposits,  containing  alumina  or  clay 
as  their  essential  ingredient,  it  cannot  be  said  that  any  of  these 
have  been  actually  shown  to  be  of  organic  origin.  A  recent 
observation  by  Sir  Wyville  Thomson  would,  however,  render  it 
not  improbable  that  some  of  the  great  argillaceous  accumulations 
of  past  geological  periods  may  be  really  organic.  This  dis- 
tinguished observer,  during  the  cruise  of  the  Challenger,  showed 
that  the  calcareous  ooze  which  has  been  already  spoken  of  as 
covering  large  areas  of  the  floor  of  the  Atlantic  and  Pacific  at 
great  depths,  and  which  consists  almost  wholly  of  the  shells  of 
Foraminifera,  gave  place  at  still  greater  depths  to  a  red  ooze  con- 
sisting of  impalpable  clayey  mud,  colored  by  oxide  of  iron,  and 
devoid  of  traces  of  organic  bodies.  As  the  existence  of  this 
widely-diffused  red  ooze,  in  mid-ocean,  and  at  such  great  depths, 
cannot  be  explained  on  the  supposition  that  it  is  a  sediment 
brought  down  into  the  sea  by  rivers,  Sir  Wyville  Thomson  came 
to  the  conclusion  that  it  was  probably  formed  by  the  action  of  the 
sea-water  upon  the  shells  of  Foraminifera.  These  shells,  though 
mainly  consisting  of  lime,  also  contain  a  certain  proportion  of 
alumina,  the  former  being  soluble  in  the  carbonic  acid  dissolved 
in  the  sea-water,  whilst  the  latter  is  insoluble.  There  would 
further  appear  to  be  grounds  for  believing  that  the  solvent  power 
of  the  sea-water  over  lime  is  considerable  increased  at  great 
depths.  If,  therefore,  we  suppose  the  shells  of  Foraminifera 
to  be  in  course  of  deposition  over  the  floor  of  the  Pacific,  at 
certain  depths  they  would  remain  unchanged,  and  would  ac- 
cumulate to  form  a  calcareous  ooze;  but  at  greater  depths  they 
would  be  acted  upon  by  the  water,  their  lime  would  be  dis- 
solved out,  their  form  would  disappear,  and  we  should  simply  have 
left  the  small  amount  of  alumina  which  they  previously  contained. 


THE  FOSSILIFEROUS  ROCKS.  37 

In  process  of  time  this  alumina  would  accumulate  to  form  a  bed 
of  clay;  aad  as  this  clay  has  been  directly  derived  from  the 
decomposition  of  the  shells  of  animals,  it  would  be  fairly  entitled 
to  be  considered  an  organic  deposit.  Though  not  finally  estab- 
lished, the  hypothesis  of  Sir  Wyville  Thomson  on  this  subject  is 
of  the  greatest  interest  to  the  palaeontologist,  as  possibly  serving 
to  explain  the  occurrence,  especially  in  the  older  formations,  of 
great  deposits  of  argillaceous  matter  which  are  entirely  destitute 
of  traces  of  life. 

It  only  remains,  in  this  connection,  to  shortly  consider  the 
rock-deposits  in  which  carbon  is  found  to  be  present  in  greater 
or  less  quantity.  In  the  great  majority  of  cases  where  rocks 
are  found  to  contain  carbon  or  carbonaceous  matter,  it  can  be 
stated  with  certainty  that  this  substance  is  of  organic  origin, 
though  it  is  not  necessarily  derived  from  vegetables.  Carbon 
derived  from  the  decomposition  of  animal  bodies  is  not  uncom- 
mon ;  though  it  never  occurs  in  such  quantity  from  this  source 
as  it  may  do  when  it  is  derived  from  plants.  Thus,  many 
limestones  are  more  or  less  highly  bituminous ;  the  celebrated 
siliceous  flags  or  so-called  "  bituminous  schists  "  of  Caithness  are 
impregnated  with  oily  matter  apparently  derived  from  the  decom- 
position of  the  numerous  fishes  embedded  in  them ;  Silurian 
shales  containing  Graptolites,  but  destitute  of  plants,  are  not 
uncommonly  "  anthracitic, "  and  contain  a  small  percentage  of 
carbon  derived  from  the  decay  of  these  zoophytes;  whilst  the 
petroleum  so  largely  worked  in  North  America  has  not  im- 
probably an  animal  origin.  That  the  fatty  compounds  present 
in  animal  bodies  should  more  or  less  extensively  impregnate 
fossiliferous  rock-masses,  is  only  what  might  be  expected;  but 
the  great  bulk  of  the  carbon  which  exists  stored  up  in  the 
earth's  crust  is  derived  from  plants;  and  the  form  in. which  it 
principally  presents  itself  is  that  of  coal.  We  shall  have  to  speak 
again,  and  at  greater  length,  of  coal,  and  it  is  sufficient  to  say 
here  that  all  the  true  coals,  anthracites,  and  lignites,  are  of 
organic  origin,  and  consist  principally  of  the  remains  of  plants 
in  a  more  or  less  altered  condition.  The  bituminous  shales 
which  are  found  so  commonly  associated  with  beds  of  coal  also 
derive  their  carbon  primarily  from  plants;  and  the  same  is 
certainly,  or  probably,  the  case  with  similar  shales  which  are 
known  to  occur  in  formations  younger  than  the  Carboniferous. 
Lastly,  carbon  may  occur  as  a  conspicuous  constituent  of  rock- 
masses  in  the  form  of  graphite  or  black-lead.  In  this  form,  it 
occurs  in  the  shape  of  detached  scales,  of  veins  or  strings,  or 


38  PRINCIPLES  OF  PALAEONTOLOGY. 

sometimes  of  regular  layers ;  *  and  there  can  be  little  doubt  that 
in  many  instances  it  has  an  organic  origin,  though  this  is  not 
capable  of  direct  proof.  When  present,  at  any  rate,  in  quantity, 
and  in  the  form  of  layers  associated  with  stratified  rocks,  as  is 
often  the  case  in  the  Laurentian  formation,  there  can  be  little 
hesitation  in  regarding  it  as  of  vegetable  origin,  and  as  an 
altered  coal. 


CHAPTER  III. 

CHRONOLOGICAL  SUCCESSION  OF  THE 
FOSSILIFEROUS  ROCKS. 

The  physical  geologist,  who  deals  with  rocks  simply  as  rocks, 
and  who  does  not  necessarily  trouble  himself  about  what  fossils 
they  may  contain,  finds  that  the  stratified  deposits  which  form 
so  large  a  portion  of  the  visible  part  of  the  earth's  crust  are 
not  promiscuously  heaped  together,  but  that  they  have  a  cer- 
tain definite  arrangement.  In  each  country  that  he  examines, 
he  finds  that  certain  groups  of  strata  lie  above  certain  other 
groups ;  and  in  comparing  different  countries  with  one  another, 
he  finds  that,  in  the  main,  the  same  groups  of  rocks  are  always 
found  in  the  same  relative  position  to  each  other.  It  is  pos- 
sible, therefore,  for  the  physical  geologist  to  arrange  the  known 
stratified  rocks  into  a  successive  series  of  groups,  or  "  forma- 
tions, "  having  a  certain  definite  order.  The  establishment  of 
this  physical  order  amongst  the  rocks  introduces,  however,  at 
once  the  element  of  time,  and  the  physical  succession  of  the 
strata  can  be  converted  directly  into  a  historical  or  chronolog- 
ical succession.  This  is  obvious,  when  we  reflect  that  any  bed 
or  set  of  beds  of  sedimentary  origin  is  clearly  and  necessarily 

*  In  the  Huronian  formation  of  Steel  River,  on  the  north  shore  of 
Lake  Superior,  there  exists  a  bed  of  carbonaceous  matter  which  is  regu- 
larly interstratified  with  the  surrounding  rocks,  and  has  a  thickness  of 
from  30  to  40  feet.  This  bed  is  shown  by  chemical  analysis  to  contain 
about  50  per  cent  of  carbon,  partly  in  the  form  of  graphite,  partly  in  the 
form  of  anthracite;  and  there  can  be  little  doubt  but  that  it  is  really  a 
stratum  of  "  metamorphic  "  coal. 


CHRONOLOGICAL  SUCCESSION.  39 

younger  than  all  the  strata  upon  which  it  rests,  and  older  than 
all  those  by  which  it  is  surmounted. 

It  is  possible,  then,  by  an  appeal  to  the  rocks  alone,  to  de- 
termine in  each  country  the  general  physical  succession  of  the 
strata,  and  this  "  stratigraphical "  arrangement,  when  once  de- 
termined, gives  us  the  relative  ages  of  the  successive  groups. 
The  task,  however,  of  the  physical  geologist  in  this  matter  is 
immensely  lightened  when  he  calls  in  palaeontology  to  his  aid, 
and  studies  the  evidence  of  the  fossils  embedded 'in  the  rocks. 
Not  only  is  it  thus  much  easier  to  determine  the  order  of  suc- 
cession of  the  strata  in  any  given  region,  but  it  becomes  now 
for  the  first  time  possible  to  compare,  with  certainty  and  pre- 
cision, the  order  of  succession  in  one  region  with  that  which 
exists  in  other  regions  far  distant.  The  value  of  fossils  as  tests 
of  the  relative  ages  of  the  sedimentary  rocks  depends  on  the 
fact  that  they  are  not  indefinitely  or  promiscuously  scattered 
through  the  crust  of  the  earth, — as  it  is  conceivable  that  they 
might  be.  On  the  contrary,  the  first  and  most  firmly  estab- 
lished law  of  Palaeontology  is,  that  particular  kinds  of  fossils 
are  confined  to  particular  rocks,  and  particular  groups  of  fossils 
are  confined  to  particular  groups  of  rocks.  Fossils,  then,  are 
distinctive  of  the  rocks  in  which  they  are  found — much  more 
distinctive,  in  fact,  than  the  mere  mineral  character  of  the  rock 
can  be,  for  that  commonly  changes  as  a  formation  is  traced 
from  one  region  to  another,  whilst  the  fossils  remain  unaltered. 
It  would  therefore  be  quite  possible  for  the  palaeontologist, 
by  an  appeal  to  the  fossils  alone,  to  arrange  the  series  of  sedi- 
mentary deposits  into  a  pile  of  strata  having  a  certain  definite 
order.  Not  only  would  this  be  possible,  but  it  would  be  found 
— if  sufficient  knowledge  had  been  brought  to  bear  on  both 
sides — that  the  palaeontological  arrangement  of  the  strata  would 
coincide  in  its  details  with  the  stratigraphical  or  physical 
arrangement. 

Happily  for  science,  there  is  no  such  division  between  the 
palaeontologist  and  the  physical  geologist  as  here  supposed ; 
but  by  the  combined  researches  of  the  two,  it  has  been  found 
possible  to  divide  the  entire  series  of  stratified  deposits  into  a 
number  of  definite  rock-groups  or  formations,  which  have  a 
recognized  order  of  succession,  and  each  of  which  is  charac- 
terized by  possessing  an  assemblage  of  organic  remains  which 
do  not  occur  in  association  in  any  other  formation.  Such  an 
assemblage  of  fossils,  characteristic  of  any  given  formation,  rep- 
resents the  life  of  the  particular  period  in  which  the  formation 


40  PRINCIPLES  OF  PALEONTOLOGY. 

was  deposited.  In  this  way  the  past  history  of  the  earth 
becomes  divided  into  a  series  of  successive  life- periods,  each  of 
which  corresponds  with  the  deposition  of  a  particular  forma- 
tion or  group  of  strata. 

Whilst  particular  assemblages  of  organic  forms  characterize 
particular  groups  of  rocks,  it  may  be  further  said  that,  in  a 
general  way,  each  subdivision  of  each  formation  has  its  own 
peculiar  fossils,  by  which  it  may  be  recognized  by  a  skilled 
worker  in  Palaeontology.  Whenever,  for  instance,  we  meet 
with  examples  of  the  fossils  which  are  known  as  Graptolites,  we 
may  be  sure  that  we  are  dealing  with  Silurian  rocks  (leaving 
out  of  sight  one  or  two  forms  doubtfully  referred  to  this  family). 
We  may,  however,  go  much  further  than  this  with  perfect 
safety.  If  the  Graptolites  belong  to  certain  genera,  we  may 
be  quite  certain  that  we  are  dealing  with  Lower  Silurian  rocks. 
Furthermore,  if  certain  special  forms  are  present,  we  may  be 
even  able  to  say  to  what  exact  subdivision  of  the  Lower  Silurian 
series  they  belong. 

As  regards  particular  fossils,  however,  or  even  particular 
classes  of  fossils,  conclusions  of  this  nature  require  to  be  accom- 
panied by  a  tacit  but  well-understood  reservation.  So  far  as 
our  present  observation  goes,  none  of  the  undoubted  Grapto- 
lites have  ever  been  discovered  in  rocks  later  than  those  known 
upon  other  grounds  to  be  Silurian ;  but  it  is  possible  that  they 
might  at  any  time  be  detected  in  younger  deposits.  Similarly, 
the  species  and  genera  which  we  now  regard  as  characteristic 
of  the  Lower  Silurian,  may  at  some  future  time  be  found  to 
have  survived  into  the  Upper  Silurian  period.  We  should  not 
forget,  therefore,  in  determining  the  age  of  strata  by  palseonto- 
logical  evidence,  that  we  are  always  reasoning  upon  generaliza- 
tions which  are  the  result  of  experience  alone,  and  which  are 
liable  to  be  vitiated  by  further  and  additional  discoveries. 

When  the  palaeontological  evidence  as  to  the  age  of  any 
given  set  of  strata  is  corroborated  by  the  physical  evidence,  our 
conclusions  may  be  regarded  as  almost  certain;  but  there  are 
certain  limitations  and  fallacies  in  the  palseontological  method 
of  inquiry  which  deserve  a  passing  mention.  In  the  first 
place,  fossils  are  not  always  present  in  the  stratified  rocks; 
many  aqueous  rocks  are  unfossiliferous,  through  a  thickness  of 
hundreds  or  even  thousands  of  feet  of  little-altered  sediments; 
and  even  amongst  beds  which  do  contain  fossils,  we  often  meet 
with  strata  of  many  feet  or  yards  in  thickness  which  are  wholly 
destitute  of  any  traces  of  fossils.  There  are,  therefore,  to 


CHRONOLOGICAL  SUCCESSION.  41 

begin  with,  many  cases  in  which  there  is  no  palaeontological 
evidence  extant  or  available  as  to  the  age  of  a  given  group 
of  strata.  In  the  second  place,  palaeontological  observers  in 
different  parts  of  the  world  are  liable  to  give  different  names 
to  the  same  fossils,  and  in  all  parts  of  the  world  they  are  occa- 
sionally liable  to  group  together  different  fossils  under  the 
same  title.  Both  these  sources  of  fallacy  require  to  be  guarded 
against  in  reasoning  as  to  the  age  of  strata  from  their  fossil 
remains.  Thirdly,  the  mere  fact  of  fossils  being  found  in  beds 
which  are  known  by  physical  evidence  to  be  of  different  ages, 
has  commonly  led  palaeontologists  to  describe  them  as  dif»- 
ferent  species.  Thus  the  same  fossil,  occurring  in  successive 
groups  of  strata,  and  with  the  merely  trivial  and  varietal  differ- 
ences due  to  the  gradual  change  in  its  environment,  has  been 
repeatedly  described  as  a  distinct  species,  with  a  distinct  name, 
in  every  bed  in  which  it  was  found.  We  know,  however,  that 
many  fossils  range  vertically  through  many  groups  of  strata,  and 
there  are  some  which  even  pass  through  several  formations. 
The  mere  fact  of  a  difference  of  physical  position  ought  never 
to  be  taken  into  account  at  all  in  considering  and  determining 
the  true  affinities  of  a  fossil.  Fourthly,  the  results  of  experience, 
instead  of  being  an  assistance,  are  sometimes  liable  to  operate 
as  a  source  of  error.  When  once,  namely,  a  generalization  has 
been  established  that  certain  fossils  occur  in  strata  of  a  certain 
age,  palaeontologists  are  apt  to  infer  that  all  beds  containing 
similar  fossils  must  be  of  the  same  age.  There  is  a  presumption, 
of  course,  that  this  inference  would  be  correct;  but  it  is  not  a 
conclusion  resting  upon  absolute  necessity,  and  there  might  be 
physical  evidence  to  disprove  it.  Fifthly,  the  physical  geologist 
may  lead  the  palaeontologist  astray  by  asserting  that  the  physical 
evidence  as  to  the  age  and  position  of  a  given  group  of  beds  is 
clear  and  unequivocal,  when  such  evidence  may  be,  in  reality, 
very  slight  and  doubtful.  In  this  way,  the  observer  may  be 
readily  led  into  wrong  conclusions  as  to  the  nature  of  the  organic 
remains — often  obscure  and  fragmentary — which  it  is  his  business 
to  examine,  or  he  may  be  led  erroneously  to  think  that  previous 
generalizations  as  to  the  age  of  certain  kinds  of  fossils  are 
premature  and  incorrect.  Lastly,  there  are  cases  in  which,  owing 
to  the  limited  exposure  of  the  beds,  to  their  being  merely  of 
local  development,  or  to  other  causes,  the  physical  evidence  as 
to  the  age  of  a  given  group  of  strata  may  be  entirely  uncertain 
and  unreliable,  and  in  which,  therefore,  the  observer  has  to  rely 
wholly  upon  the  fossils  which  he  may  meet  with. 


42  PRINCIPLES  OF  PALAEONTOLOGY. 

In  spite  of  the  above  limitations  and  fallacies,  there  can  be 
no  doubt  as  to  the  enormous  value  of  palaeontology  in  enab- 
ling us  to  work  out  the  historical  succession  of  the  sedimentary 
rocks.  It  may  even  be  said  that  in  any  case  where  there 
should  appear  to  be  a  clear  and  decisive  discordance  between 
the  physical  and  the  palseontological  evidence  as  to  the  age 
of  a  given  series  of  beds,  it  is  the  former  that  is  to  be  distrusted 
rather  than  the  latter.  The  records  of  geological  science  con- 
tain not  a  few  cases  in  which  apparently  clear  physical  evidence 
of  superposition  has  been  demonstrated  to  have  been  wrongly 
interpreted;  but  the  evidence  of  palseontology,  when  in  any  way 
sufficient,  has  rarely  been  upset  by  subsequent  investigations. 
Should  we  find  strata  containing  plants  of  the  Coal-measures 
apparently  resting  upon  other  strata  with  Ammonites  and  Belem- 
nites,  we  may  be  sure  that  the  physical  evidence  is  delusive ;  and 
though  the  above  is  an  extreme  case,  the  presumption  in  all 
such  instances  is  rather  that  the  physical  succession  has  been 
misunderstood  or  misconstrued,  than  that  there  has  been  a  sub- 
version of  the  recognized  succession  of  life-forms. 

We  have  seen,  then,  that  as  the  collective  result  of  observa- 
tions made  upon  the  superposition  of  rocks  in  different  localities, 
from  their  mineral  characters,  and  from  their  included  fossils, 
geologists  have  been  able  to  divide  the  entire  stratified  series 
into  a  number  of  different  divisions  or  formations,  each  charac- 
terized by  a  general  uniformity  of  mineral  composition,  and  by 
a  special  and  peculiar  assemblage  of  organic  forms.  Each  of 
these  primary  groups  is  in  turn  divided  into  a  series  of  smaller 
divisions,  characterized  and  distinguished  in  the  same  way.  It  is 
not  pretended  for  a  moment  that  all  these  primary  rock-groups 
can  anywhere  be  seen  surmounting  one  another  regularly.  * 
There  is  no  region  upon  the  earth  where  all  the  stratified  forma- 
tions can  be  seen  together ;  and,  even  when  most  of  them  occur 
in  the  same  country,  they  can  nowhere  be  seen  all  succeeding 
each  other  in  their  regular  and  uninterrupted  succession.  The 
reason  of  this  is  obvious.  There  are  many  places — to  take  a 

*  As  we  have  every  reason  to  believe  that  dry  land  and  sea  have  ex- 
isted, at  any  rate  from  the  commencement  of  the  Laurentian  period  to 
the  present  day,  it  is  quite  obvious  that  no  one  of  the  great  formations 
can  ever,  under  any  circumstances,  have  extended  over  the  entire  globe. 
In  other  words,  no  one  of  the  formations  can  ever  have  had  a  greater 
geographical  extent  than  that  of  the  seas  of  the  period  in  which  the  for- 
mation was  deposited.  Nor  is  there  any  reason  for  thinking  that  the  pro- 
portion of  dry  land  to  ocean  has  ever  been  materially  different  to  what  it 
is  at  present,  however  greatly  the  areas  of  sea  and  land  may  have  changed 
as  regards  their  place.  It  follows  from  the  above,  that  there  is  no  suf- 
ficient basis  for  the  view  that  the  crust  of  the  earth  is  composed  of  a 
succession  of  concentric  layers,  like  the  coats  of  an  onion,  each  layer 
representing  one  formation. 


CHRONOLOGICAL  SUCCESSION.  43 

single  example — where  one  may  see  the  Silurian  rocks,  the 
Devonian,  and  the  Carboniferous  rocks  succeeding  one  another 
regularly,  and  in  their  proper  order.  This  is  because  the 
particular  region  where  this  occurs  was  always  submerged  be- 
neath the  sea  while  these  formations  were  being  deposited. 
There  are,  however,  many  more  localities  in  which  one  would 
find  the  Carboniferous  rocks  resting  unconformably  upon  the 
Silurians  without  the  intervention  of  any  strata  which  could  be 
referred  to  the  Devonian  period.  This  might  arise  from  one  of 
two  causes :  i.  The  Silurians  might  have  been  elevated  above  the 
sea  immediately  after  their  deposition,  so  as  to  form  dry  land 
during  the  whole  of  the  Devonian  period,  in  which  case,  of 
course,  no  strata  of  the  later  age  could  possibly  be  deposited  in 
that  area.  2.  The  Devonian  might  have  been  deposited  upon  the 
Silurian,  and  then  the  whole  might  have  been  elevated  above  the 
sea,  and  subjected  to  an  amount  of  denudation  sufficient  to 
remove  the  Devonian  strata  entirely.  In  this  case,  when  the 
land  was  again  submerged,  the  Carboniferous  rocks,  or  any 
younger  formation,  might  be  deposited  directly  upon  Silurian 
strata.  From  one  or  other  of  these  causes,  then,  or  from  subse- 
quent disturbances  and  denudations,  it  happens  that  we  can 
rarely  find  many  of  the  primary  formations  following  one 
another  consecutively  and  in  their  regular  order. 

In  no  case,  however,  do  we  ever  find  the  Devonian  resting 
upon  the  Carboniferous,  or  the  Silurian  rocks  reposing  on  the 
Devonian.  We  have  therefore,  by  a  comparison  of  many 
different  areas,  an  established  order  of  succession  of  the  strati- 
fied formations,  as  shown  in  the  subjoined  ideal  section  of  the 
crust  of  the  earth  (fig.  17). 

The  main  subdivisions  of  the  stratified  rocks  are  known  by 
the  following  names  : — 

1.  Laurentian. 

2.  Cambrian  (with  Huronian?). 

3.  Silurian. 

4.  Devonian  or  Old  Red  Sandstone. 

5.  Carboniferous. 

6.  Permian 

7.  Triassic 

8.  Jurassic  or  Oolitic. 

9.  Cretaceous. 

10.  Eocene. 

11.  Miocene. 

12.  Pliocene. 

13.  Post-tertiary. 


>  New  Red  San-dstone. 


44 


PRINCIPLES  OF  PALEONTOLOGY. 


IDEAL  SECTION  OF  THE  CRUST  OF  THE  EARTH. 
Fig.  17. 

l»     Post-tertiary  and  Recent. 
f>     Pliocene. 

^.V^^^^o^Fvjr^^yH  r     Miocene. 


Eocene. 
Cretaceous. 

Oolitic  or  Jurassic. 

Triassic. 
Permian. 

Carboniferous. 


Devonian    or    Old    Red    Sand- 
stone. 


Silurian. 

Cambrian. 
Huronian. 

Laurentian. 


CHRONOLOGICAL  SUCCESSION.  45 

Of  these  primary  rock  divisions,  the  Laurentian,  Cambrian, 
Silurian,  Devonian,  Carboniferous,  and  Permian  are  collectively 
grouped  together  under  the  name  of  the  Primary  or  Pal&ozoic 
rocks  (G.  palaios,  ancient;  zoe,  life).  Not  only  do  they  constitute 
the  oldest  stratified  accumulations,  but  from  the  extreme  diver- 
gence between  their  animals  and  plants  and  those  now  in  exist- 
ence, they  may  appropriately  be  considered  as  belonging  to  an 
"  Old-Life "  period  of  the  world's  history.  The  Triassic, 
Jurassic,  and  Cretaceous  systems  are  grouped  together  as  the 
Secondary  or  Mesozoic  formations  (Gr.  mesos,  intermediate; 
zoe,  life);  the  organic  remains  of  this  "  Middle-  Life "  period 
being,  on  the  whole,  intermediate  in  their  characters  between 
those  of  the  palaeozoic  epoch  and  those  of  more  modern  strata. 
Lastly,  the  Eocene,  Miocene,  and  Pliocene  formations  are 
grouped  together  as  the  Tertiary  or  Kainozoic  rocks  (Gr.  kainos, 
new;  zoe,  life)  ;  because  they  constitute  a  "New-Life"  period,  in 
which  the  organic  remains  approximate  in  character  to  those  now 
existing  upon  the  globe.  The  so-called  Post-Tertiary  deposits  are 
placed  with  the  Kainozoic,  or  may  be  considered  as  forming  a 
separate  Quaternary  system. 


CHAPTER  IV. 

THE  BREAKS  IN  THE  GEOLOGICAL  AND 
PALMONTOLOGICAL  RECORD. 

The  term  "  contemporaneous "  is  usually  applied  by  geolo- 
gists to  groups  of  strata  in  different  regions  which  contain  the 
same  fossils,  or  an  assemblage  of  fossils  in  which  many  iden- 
tical forms  are  present.  That  is  to  say,  beds  which  contain 
identical,  or  nearly  identical,  fossils,  however  widely  separated 
they  may  be  from  one  another  in  point  of  actual  distance,  are 
ordinarily  believed  to  have  been  deposited  during  the  same 
period  of  the  earth's  history.  This  belief,  indeed,  constitutes 
the  keystone  of  the  entire  system  of  determining  the  age  of 
strata  by  their  fossil  contents;  and  if  we  take  the  word  "con- 
temporaneous "  in  a  general  and  strictly  geological  sense,  this 
belief  can  be  accepted  as  proved  beyond  denial.  We  must, 
however,  guard  ourselves  against  too  literal  an  interpretation 


46  PRINCIPLES  OF  PALEONTOLOGY. 

of  the  word  "  contemporaneous, "  and  we  must  bear  in  mind 
the  enormously-prolonged  periods  of  time  with  which  the 
geologist  has  to  deal.  When  we  say  that  two  groups  of  strata 
in  different  regions  are  "  contemporaneous, "  we  simply  mean 
that  they  were  formed  during  the  same  geological  period,  and 
perhaps  at  different  stages  of  that  period,  and  we  do  not  mean  to 
imply  that  they  were  formed  at  precisely  the  same  instant  of  time. 
A  moment's  consideration  will  show  us  that  it  is  only  in  the 
former  sense  that  we  can  properly  speak  of  strata  being  "  con- 
temporaneous ;  "  and  that,  in  points  of  fact,  beds  containing 
the  same  fossils,  if  occurring  in  widely  distant  areas,  can  hardly 
be  "  contemporaneous "  in  any  literal  sense ;  but  that  the  very 
identity  of  their  fossils  is  proof  that  they  were  deposited  one 
after  the  other.  If  we  find  strata  containing  identical  fossils 
within  the  limits  of  a  single  geographical  region — say  in  Europe 
— then  there  is  a  reasonable  probability  that  these  beds  are 
strictly  contemporaneous,  in  the  sense  that  they  were  deposited 
at  the  same  time.  There  is  a  reasonable  probability  of  this, 
because  there  is  no  improbability  involved  in  the  idea  of  an 
ocean  occupying  the  whole  area  of  Europe,  and  peopled 
throughout  by  many  of  the  same  species  of  marine  animals.  At 
the  present  day,  for  example,  many  identical  species  of  animals 
are  found  living  on  the  .western  coasts  of  Britain  and  the  eastern 
coasts  of  North  America,  and  beds  now  in  course  of  deposition 
off  the  shores  of  Ireland  and  the  seaboard  of  the  state  of 
New  York  would  necessarily  contain  many  of  the  same  fossils. 
Such  beds  would  be  both  literally  and  geologically  contempora- 
neous ;  but  the  case  is  different  if  the  distance  between  the  areas 
where  the  strata  occur  be  greatly  increased.  We  find,  for  ex- 
ample, beds  containing  identical  fossils  (the  Quebec  or  Skiddaw 
beds)  in  Sweden,  in  the  north  of  England,  in  Canada,  and  in 
Australia.  Now,  if  all  these  beds  were  contemporaneous,  in  the 
literal  sense  of  the  term,  we  should  have  to  suppose  that  the 
ocean  at  one  time  extended  uninterruptedly  between  all  these 
points,  and  was  peopled  throughout  the  vast  area  thus  indicated 
by  many  of  the  same  animals.  Nothing,  however,  that  we  see  at 
the  present  day  would  justify  us  in  imagining  an  ocean  of  such 
enormous  extent,  and  at  the  same  time  so  uniform  in  its  depth, 
temperature,  and  other  conditions  of  marine  life,  as  to  allow 
the  same  animals  to  flourish  in  it  from  end  to  end ;  and  the 
example  chosen  is  only  one  of  a  long  and  ever-recurring  series. 
It  is  therefore  much  more  reasonable  to  explain  this,  and  all 
similar  cases,  as  owing  to  the  migration  of  the  fauna,  in  whole 


BREAKS  IN  THE  GEOLOGICAL  RECORD.     47 

or  in  part,  from  one  marine  area  to  another.  Thus,  we  may 
suppose  an  ocean  to  cover  what  is  now  the  European  area,  and 
to  be  peopled  by  certain  species  of  animals.  Beds  of  sediment — 
clay,  sands,  and  limestones — will  be  deposited  over  the  sea- 
bottom,  and  will  entomb  the  remains  of  the  animals  as  fossils. 
After  this  has  lasted  fof  a  certain  length  of  time,  the  European 
area  may  undergo  elevation,  or  may  become  otherwise  unsuitable 
for  the  perpetuation  of  its  fauna;  the  result  of  which  would  be 
that  some  or  all  of  the  marine  animals  of  the  area  would  migrate 
to  some  more  suitable  region.  Sediments  would  then,  be  accumu- 
lated in  the  new  area  to  which  they  had  betaken  themselves, 
and  they  would  then  appear,  for  the  second  time,  as  fossils  in 
a  set  of  beds  widely  separated  from  Europe.  The  second  set 
of  beds  would,  however,  obviously  not  be  strictly  or  literally 
contemporaneous  with  the  first,  but  would  be  separated  from 
them  by  the  period  of  time  required  for  the  migration  of  the 
animals  from  the  one  area  into  the  other.  It  is  only  in  a  wide 
and  comprehensive  sense  that  such  strata  can  be  said  to  be  con- 
temporaneous. 

It  is  impossible  to  enter  further  into  this  subject  here;  but  it 
may  be  taken  as  certain  that  beds  in  widely  remote  geographical 
areas  can  only  come  to  contain  the  same  fossils  by  reason  of  a 
migration  having  taken  place  of  the  animals  of  the  one  area  to 
the  other.  That  such  migrations  can  and  do  take  place  is  quite 
certain,  and  this  is  a  much  more  reasonable  explanation  of  the 
observed  facts  than  the  hypothesis  that  in  former  periods  the 
conditions  of  life  were  much  more  uniform  than  they  are  at 
present,  and  that,  consequently,  the  same  organisms  were  able 
to  range  over  the  entire  globe  at  the  same  time.  It  need  only  be 
added,  that  taking  the  evidence  of  the  present  as  explaining  the 
phenomena  of  the  past — the  only  safe  method  of  reasoning  in 
geological  matters — we  have  abundant  proof  that  deposits  which 
are  actually  contemporaneous,  in  the  strict  sense  of  the  term, 
do  not  contain  the  same  fossils,  if  far  removed  from  one  another 
in  point  of  distance.  Thus,  deposits  of  various  kinds  are  now 
in  process  of  formation  in  our  existing  seas,  as  for  example,  in. 
the  Arctic  Ocean,  the  Atlantic,  and  the  Pacific,  and  marfy  of 
these  deposits  are  known  to  us  by  actual  examination  and  obser- 
vation with  the  sounding-lead  and  dredge.  But  it  is  hardly  neces- 
sary to  add  that  the  animal  remains  contained  in  these  deposits — 
the  fossils  of  some  future  period — instead  of  being  identical,  are 
widely  different  from  one  another  in  their  characters. 

We    have    seen,    then,    that    the    entire    stratified    series    is 


48  PRINCIPLES  OF  PALAEONTOLOGY. 

capable  of  subdivision  into  a  number  of  definite  rock-groups  or 
"  formations, "  each  possessing  a  peculiar  and  characteristic 
assemblage  of  fossils,  representing  the  "  life  "  of  the  "  period  "  in 
which  the  formation  was  deposited.  We  have  still  to  inquire 
shortly  how  it  came  to  pass  that  two  successive  formations 
should  thus  be  broadly  distinguished  by  their  life-forms,  and 
why  they  should  not  rather  possess  at  any  rate  a  majority  of 
identical  fossils.  It  was  originally  supposed  that  this  could  be 
explained  by  the  hypothesis  that  the  close  of  each  formation 
was  accompanied  by  a  general  destruction  of  all  the  living 
beings  of  the -period,  and  that  the  commencement  of  each  new 
formation  was  signalized  by  the  creation  of  a  number  of  brand- 
new  organisms,  destined  to  figure  as  the  characteristic  fossils  of 
the  same.  This  theory,  however,  ignores  the  fact  that 
each  formation — as  to  which  we  have  any  sufficient  evidence — 
contains  a  few,  at  least,  of  the  life-forms  which  existed  in  the 
preceding  period;  and  it  invokes  forces  and  processes  of  which 
we  know  nothing,  and  for  the  supposed  action  of  which  we  can- 
not account.  The  problem  is  an  undeniably  difficult  one,  and  it 
will  not  be  possible  here  to  give  more  than  a  mere  outline  of 
the  modern  views  upon  the  subject.  Without  entering  into  the  at 
present  inscrutable  question  as  to  the  manner  in  which  new  life- 
forms  are  introduced  upon  the  earth,  it  may  be  stated  that  almost 
all  modern  geologists  hold  that  the  living  beings  of  any  given 
formation  are  in  the  main  modified  forms  of  others  which  have 
preceded  them.  It  is  not  believed  that  any  general  or  universal 
destruction  of  life  took  place  at  the  termination  of  each  geolog- 
ical period,  or  that  a  general  introduction  of  new  forms  took 
place  at  the  commencement  of  a  new  period.  It  is,  on  the  con- 
trary, believed  that  the  animals  and  plants  of  any  given  period 
are  for  the  most  part  (or  exclusively)  the  lineal  but  modified 
descendants  of  the  animals  and  plants  of  the  immediately  pre- 
ceding period,  and  that  some  of  them,  at  any  rate,  are  continued 
into  the  next  succeeding  period,  either  unchanged,  or  so  far 
altered  as  to  appear  as  new  species.  To  discuss  these  views  in 
detail  would  lead  us  altogether  too  far,  but  there  is  one  very 
obvious  consideration  which  may  advantageously  receive  some 
attention.  It  is  obvious,  namely,  that  the  great  discordance  which 
is  found  to  subsist  between  the  animal  life  of  any  given  forma- 
tion and  that  of  the  next  succeeding  formation,  and  which  no 
one  denies,  would  be  a  fatal  blow  to  the  views  just  alluded  to, 
unless  admitting  of  some  satisfactory  explanation.  Nor  is  this 
discordance  one  purely  of  life-forms,  for  there  is  often  a  physical 


BREAKS  IN  THE  GEOLOGICAL  RECORD.     49 

break  in  the  successions  of  strata  as  well.  Let  us  therefore 
briefly  consider  how  far  these  interruptions  and  breaks  in  the 
geological  and  palaeontological  record  can  be  accounted  for,  and 
still  allow  us  to  believe  in  some  theory  of  continuity  as  opposed 
to  the  doctrine  of  intermittent  and  occasional  action. 

In  the  first  place,  it  is  perfectly  clear  that  if  we  admit  the 
conception  above  mentioned  of  a  continuity  of  life  from  the 
Laurentian  period  to  the  present  day,  we  could  never  prove 
our  view  to  be  correct,  unless  we  could  produce  in  evidence 
fossil  examples  of  all  the  kinds  of  animals  and  plants  that 
have  lived  and  died  during  that  period.  In  order  to  do  this, 
we  should  require,  to  begin  with,  to  have  access  to  an  abso- 
lutely unbroken  and  perfect  succession  of  all  the  deposits  which 
have  ever  been  laid  down  since  the  beginning.  If,  however,  we 
ask  the  physical  geologist  if  he  is  in  possession  of  any  such 
uninterrupted  series,  he  will  at  once  answer  in  the  negative.  So 
far  from  the  geological  series  being  a  perfect  one,  it  is  inter- 
rupted by  numerous  gaps  of  unknown  length,  many  of  which  we 
can  never  expect  to  fill  up.  Nor  are  the  proofs  of  this  far  to  seek. 
Apart  from  the  facts  that  we  have  hitherto  examined  only  a 
limited  portion  of  the  dry  land,  that  nearly  two-thirds  of  the 
entire  area  of  the  globe  is  inaccessible  to  geological  investigation 
in  consequence  of  its  being  covered  by  the  sea,  that  many  deposits 
can  be  shown  to  have  been  more  or  less  completely  destroyed 
subsequent  to  their  deposition,  and  that  there  may  be  many 
areas  in  which  living  beings  exist  where  no  rock  is  in  process  of 
formation,  we  have  the  broad  fact  that  rock-deposition  only  goes 
on  to  any  extent  in  water,  and  that  the  earth  must  have  always 
consisted  partly  of  dry  land  and  partly  of  water — at  any  rate,  so 
far  as  any  period  of  which  we  have  geological  knowledge  is 
concerned.  There  must,  therefore,  always  have  existed,  at  some 
part  or  another  of  the  earth's  surface,  areas  where  no  deposition 
of  rock  was  going  on,  and  the  proof  of  this  is  to  be  found  in 
the  well-known  phenomenon  of  "  unconformability. "  When- 
ever, namely,  deposition  of  sediment  is  continuously  going  on 
within  the  limits  of  a  single  ocean,  the  beds  which  are  laid  down 
succeed  one  another  in  uninterrupted  and  regular  sequence.  Such 
beds  are  said  to  be  "  conformable, "  and  there  are  many  rock- 
groups  known  where  one  may  pass  through  fifteen  or  twenty 
thousand  feet  of  strata  without  a  break — indicating  that  the 
beds  had  been  deposited  in  an  area  which  remained  continu- 
ously covered  by  the  sea.  On  the  other  hand,  we  commonly 
find  that  there  is  no  such  regular  succession  when  we  pass 
4 


50  PRINCIPLES  OF  PALAEONTOLOGY. 

from  one  great  formation  to  another,  but  that,  on  the  contrary, 
the  younger  formation  rests  "  unconformably, "  as  it  is  called, 
either  upon  the  formation  immediately  preceding  it  in  point  of 
time,  or  upon  some  still  older  one.  The  essential  physical 
feature  of  this  unconformability  is  that  the  beds  of  the  younger 
formation  rest  upon  a  worn  and  eroded  surface  formed  by  the 
beds  of  the  older  series  (fig.  18)  ;  and  a  moment's  considera- 
tion will  show  us  what  this  indicates.  It  indicates,  beyond  the 


Fig.  18. — Section  showing  strata  of  Tertiary  age  (a)  resting  upon  a  worn  and  eroded 
surface  of  White  Chalk  (b),  the  stratification  of  which  is  marked  by  lines  of  flint. 

possibility  of  misconception,  that  there  was  an  interval  between 
the  deposition  of  the  older  series  and  that  of  the  newer  series  of 
strata;  and  that  during  this  interval  the  older  beds  were  raised 
above  the  sea-level,  so  as  to  form  dry  land,  and  were  subsequently 
depressed  again  beneath  the  waters,  to  receive  upon  their  worn 
and  wasted  upper  surface  the  sediments  of  the  later  group. 
During  the  interval  thus  indicated,  the  deposition  of  rock  must 
of  necessity  have  been  proceeding  more  or  less  actively  in  other 
areas.  Every  unconformity,  therefore,  indicates  that  at  the 
spot  where  it  occurs,  a  more  or  less  extensive  series  of  beds  must 
be  actually  missing;  and  though  we  may  sometimes  be  able  to 
point  to  these  missing  strata  in  other  areas,  there  yet  remains  a 
number  of  unconformities  for  which  we  cannot  at  present  supply 
the  deficiency  even  in  a  partial  manner. 

It  follows  from  the  above  that  the  series  of  stratified  deposits 
is  to  a  greater  or  less  extent  irremediably  imperfect;  and  in 
this  imperfection  we  have  one  great  cause  why  we  can  never 
obtain  a  perfect  series  of  all  the  animals  and  plants  that  have 
lived  upon  the  globe.  Wherever  one  of  these  great  physical 
gaps  occurs,  we  find,  as  we  might  expect,  a  corresponding  break 
in  the  series  of  life-forms.  In  other  words,  whenever  we 


BREAKS  IN  THE  GEOLOGICAL  RECORD.     51 

find  two  formations  to  be  unconformable,  we  shall  always  find 
at  the  same  time  that -there  is  a  great  difference  in  their  fossils, 
and  that  many  of  the  fossils  of  the  older  formation  do  not  sur- 
vive into  the  newer,  whilst  many  of  those  in  the  newer  are  not 
known  to  occur  in  the  older.  The  cause  of  this  is,  obviously, 
that  the  lapse  of  time,  indicated  by  the  unconformability,  has 
been  sufficiently  great  to  allow  of  the  dying  out  or  modification 
of  many  of  the  older  forms  of  life,  and  the  introduction  of 
new  ones  by  immigration. 

Apart,  however,  altogether,  from  these  great  physical  breaks 
and  their  corresponding  breaks  in  life,  there  are  other  reasons 
why  we  can  never  become  more  than  partially  acquainted  with 
the  former  denizens  of  the  globe.  Foremost  amongst  these  is 
the  fact  that  an  enormous  number  of  animals  possess  no  hard 
parts  of  the  nature  of  a  skeleton,  and  are  therefore  incapable, 
under  any  ordinary  circumstances,  of  leaving  behind  them  any 
traces  of  their  existence.  It  is  true  that  there  are  cases  in 
which  animals  in  themselves  completely  soft-bodied  are  never- 
theless able  to  leave  marks  by  which  their  former  presence  can 
be  detected.  Thus  every  geologist  is  familiar  with  the  wind- 
ing and  twisting  "  trails "  formed  on  the  surface  of  the  strata 
by  sea-worms ;  and  the  impressions  left  by  the  stranded 
carcases  of  Jelly-fishes  on  the  fine-grained  lithographic  slates 
of  Solenhofen  supply  us  with  an  example  of  how  a  creature 
which  is  little  more  than  "  organized  sea-water "  may  still  make 
an  abiding  mark  upon  the  sands  of  time.  As  a  general  rule, 
however,  animals  which  have  no  skeletons  are  incapable  of 
being  preserved  as  fossils,  and  hence  there  must  always  have 
been  a  vast  number  of  different  kinds  of  marine  animals  of 
which  we  have  absolutely  no  record  whatever.  Again,  almost 
all  the  fossiliferous  rocks  have  been  laid  down  in  water ;  and 
it  is  a  necessary  result  of  this  that  the  great  majority  of  fossils 
are/  the  remains  of  aquatic  animals.  The  remains  of  air- 
breathing  animals,  whether  of  the  inhabitants  of  the  land  or  of 
the  air  itself,  are  comparatively  rare  as  fossils,  and  the  record  of 
the  past  existence  of  these  is  much  more  imperfect  than  is  the 
case  with  animals  living  in  water.  Moreover,  the  fossiliferous 
deposits  are  not  only  almost  exclusively  aqueous  formations, 
but  the  great  majority  are  marine,  and  only  a  comparatively 
small  number  have  been  formed  by  lakes  and  rivers.  It  follows 
from  the  foregoing  that  the  palaeontological  record  is  fullest  and 
most  complete  so  far  as  sea-animals  are  concerned,  though  even 
here  we  find  enormous  gaps,  owing  to  the  absence  of  hard  struc- 


52  PRINCIPLES  OF  PALAEONTOLOGY. 

tures  in  many  great  groups ;  of  animals  inhabiting  fresh  water 
our  knowledge  is  rendered  still  further  incomplete  by  the  small 
proportion  that  fluviatile  and  lacustrine  deposits  bear  to  marine ; 
whilst  we  have  only  a  fragmentary  acquaintance  with  the  air- 
breathing  animals  which  inhabited  the  earth  during  past  ages. 

Lastly,  the  imperfection  of  the  palaeontological  record,  due 
to  the  causes  above  enumerated,  is  greatly  aggravated,  espe- 
cially as  regards  the  earlier  portion  of  the  earth's  history,  by  the 
fact  that  many  rocks  which  contained  fossils  when  deposited 
have  since  been  rendered  barren  of  organic  remains.  The 
principal  cause  of  this  common  phenomenon  is  what  is  known 
as  "  metamorphism " — that  is,  the  subjection  of  the  rock  to  a 
sufficient  amount  of  heat  to  cause  a  rearrangement  of  its  par- 
ticles. When  at  all  of  a  pronounced  character,  the  result  of 
metamorphic  action  is  invariably  the  obliteration  of  any  fossils 
which  might  have  been  originally  present  in  the  rock.  Meta- 
morphism may  effect  rocks  of  any  age,  though  naturally  more 
prevalent  in  the  older  rocks,  and  to  this  cause  must  be  set 
down  an  irreparable  loss  of  much  fossil  evidence.  The  most 
striking  example  which  is  to  be  found  of  this  is  the  great  Lau- 
rentian  series,  which  comprises  some  30,000  feet  of  highly- 
metamorphosed  sediments,  but  which,  with  one  not  wholly  un- 
disputed exception,  has  as  yet  yielded  no  remains  of  living 
beings,  though  there  is  strong  evidence  of  the  former  existence 
in  it  of  fossils. 

Upon  the  whole,  then,  we  cannot  doubt  that  the  earth's 
crust,  so  far  as  yet  deciphered  by  us,  presents  us  with  but  a 
very  imperfect  record  of  the  past.  Whether  the  known  and 
admitted  imperfections  of  the  geological  and  palseontological 
records  are  sufficiently  serious  to  account  satisfactorily  for  the 
deficiency  of  direct  evidence  recognizable  in  some  modern 
hypotheses,  may  be  a  matter  of  individual  opinion.  There  can, 
however,  be  little  doubt  that  they  are  sufficiently  extensive  to 
throw  the  balance  of  evidence  decisively  in  favor  of  some  theory 
of  continuity,  as  opposed  to  any  theory  of  intermittent  and 
occasional  action.  The  apparent  breaks  which  divide  the  great 
series  of  the  stratified  rocks  into  a  number  of  isolated  forma- 
tions, are  not  marks  of  mighty  and  general  convulsions  of 
nature,  but  are  simply  indications  of  the  imperfection  of  our 
knowledge.  Never,  in  all  probability,  shall  we  be  able  to  point 
to  a  complete  series  of  deposits,  or  a  complete  succession  of 
life  linking  one  great  geological  period  to  another.  Neverthe- 
less, we  may  well  feel  sure  that  such  deposits  and  such  an 


BREAKS  IN  THE  GEOLOGICAL  RECORD.     53 

unbroken  succession  must  have  existed  at  one  time.  We  are 
compelled  to  believe  that  nowhere  in  the  long  series  of  the 
fossiliferous  rocks  has  there  been  a  total  break,  but  that  there 
must  have  been  a  complete  continuity  of  life,  and  a  more  or 
less  complete  continuity  of  sedimentation,  from  the  Laurentian 
period  to  the  present  day.  One  generation  hands  on  the  lamp 
of  life  to  the  next,  and  each  system  of  rocks  is  the  direct  off- 
spring of  those  which  preceded  it  in  time.  Though  there  has 
not  been  continuity  in  any  given  area,  still  the  geological  chain 
could  never  have  been  snapped  at  one  point,  and  taken  up 
again  at  a  totally  different  one.  Thus  we  arrive  at  the  con- 
viction that  continuity  is  the  fundamental  law  of  geology,  as  it 
is  of  the  other  sciences,  and  that  the  lines  of  demarcation  between 
the  great  formations  are  but  gaps  in  our  own  knowledge. 


CHAPTER  V. 
CONCLUSIONS  TO  BE  DRAWN  FROM  FOSSILS. 

We  have  already  seen  that  geologists  have  been  led  by  the 
study  of  fossils  to  the  all-important  generalization  that  the  vast 
series  of  the  Fossiliferous  or  Sedimentary  Rocks  may  be  divided 
into  a  number  of  definite  groups  or  "  formations, "  each  of  which 
is  characterized  by  its  organic  remains.  It  may  simply  be 
repeated  here  that  these  formations  are  not  properly  and 
strictly  characterized  by  the  occurrence  in  them  of  any  one  par- 
ticular fossil.  It  may  be  that  a  formation  contains  some 
particular  fossil  or  fossils  not  occurring  out  of  that  formation, 
and  that  in  this  way  an  observer  may  identify  a  given  group  with 
tolerable  certainty.  It  very  often  happens,  indeed,  that  some 
particular  stratum,  or  sub-group  of  series,  contains  peculiar 
fossils,  by  which  its  existence  may  be  determined  in  various 
localities.  As  before  remarked,  however,  the  great  formations 
are  characterized  properly  by  the  association  of  certain  fossils, 
by  the  predominance  of  certain  families  or  orders,  or  by  an 
assemblage  of  fossil  remains  representing  the  "  life "  of  the 
period  in  which  the  formation  was  deposited. 

Fossils,  then,  enable  us  to  determine  the  age  of  the  deposits 
in  which  they  occur.  Fossils  further  enable  us  to  come  to  very 
important  conclusions  as  to  the  mode  in  which  the  fossiliferous 
bed  was  deposited,  and  thus  as  to  the  condition  of  the  particular 
district  or  region  occupied  by  the  fossiliferous  bed  at  the  time 
of  the  formation  of  the  latter.  If,  in  the  first  place,  the  bed 


54  PRINCIPLES  OF  PALAEONTOLOGY. 

contains  the  remains  of  animals  such  as  now  inhabit  rivers,  we 
know  that  it  is  "  fluviatile "  in  its  origin,  and  that  it  must  at 
one  time  have  either  formed  an  actual  riverbed,  or  been  deposited 
by  the  overflowing  of  an  ancient  stream.  Secondly,  if  the  bed 
contain  the  remains  of  shell-fish,  minute  crustaceans,  or  fish, 
such  as  now  inhabit  lakes,  we  know  that  it  is  "  lacustrine, "  and 
was  deposited  beneath  the  waters  of  a  former  lake.  Thirdly,  if 
the  bed  contain  the  remains  of  animals  such  as  now  people  the 
ocean,  we  know  that  it  is  "  marine  "  in  its  origin,  and  that  it  is 
a  fragment  of  an  old  sea-bottom. 

We  can,  however,  often  determine  the  conditions  under 
which  a  bed  was  deposited  with  greater  accuracy  than  this.  If, 
for  example,  the  fossils  are  of  kinds  resembling  the  marine 
animals  now  inhabiting  shallow  waters,  if  they  are  accompanied 
by  the  detached  relics  of  terrestrial  organisms,  or  if  they  are 
partially  rolled  and  broken,  we  may  conclude  that  the  fossil- 
iferous  deposit  was  laid  down  in  a  shallow  sea,  in  the  immediate 
vicinity  of  a  coast-line,  or  as  an  actual  shore-deposit.  If,  again, 
the  remains  are  those  of  animals  such  as  now  live  in  the  deeper 
parts  of  the  ocean,  and  there  is  a  very  sparing  intermixture  of 
extraneous  fossils  (such  as  the  bones  of  birds  or  quadrupeds, 
or  the  remains  of  plants),  we  may  presume  that  the  deposit  is 
one  of  deep  water.  In  other  cases,  we  may  find,  scattered 
through  the  rock,  and  still  in  their  natural  position,  the  valves 
of  shells  such  as  we  know  at  the  present  day  as  living  buried 
in  the  sand  or  mud  of  the  sea-shore  or  of  estuaries.  In  other 
cases,  the  bed  may  obviously  have  been  an  ancient  coral-reef, 
or  an  accumulation  of  social  shells,  like  Oysters.  Lastly,  if  we 
find  the  deposit  to  contain  the  remains  of  marine  shells,  but 
that  these  are  dwarfed  of  their  fair  proportions  and  distorted 
in  figure,  we  may  conclude  that  it  was  laid  down  in  a  brackish 
sea,  such  as  the  Baltic,  in  which  the  proper  saltness  was  want- 
ing, owing  to  its  receiving  an  excessive  supply  of  fresh  water. 

In  the  preceding,  we  have  been  dealing  simply  with  the 
remains  of  aquatic  animals,  and  we  have  seen  that  certain  con- 
clusions can  be  accurately  reached  by  an  examination  of  these. 
As  regards  the  determination  of  the  conditions  of  deposition 
from  the  remains  of  aerial  and  terrestrial  animals,  or  from 
plants,  there  is  not  such  an  absolute  certainty.  The  remains 
of  land-animals  would,  of  course,  occur  in  "  sub-aerial "  deposits 
— that  is,  in  beds,  like  blown  sand,  accumulated  upon  the  land. 
Most  of  the  remains  of  land-animals,  however,  are  found  in 
deposits  which  have  been  laid  down  in  water,  and  they  owe 


CONCLUSIONS  TO  BE  DRAWN  FROM  FOSSILS.    55 


their  present  position  to  the  fact  that  their  former  owners  were 
drowned  in  rivers  or  lakes,  or  carried  out  to  sea  by  streams. 
Birds,  Flying  Reptiles,  and  Flying  Mammals  might  also  simi- 
larly find  their  way  into  aqueous  deposits ;  but  it  is  to  be  re- 
membered that  many  birds  and  mammals  habitually  spend  a 
great  part  of  their  time  in  the  water,  and  that  these  might  there- 
fore be  naturally  expected  to  present  themselves  as  fossils  in 
Sedimentary  Rocks.  Plants,  again,  even  when  undoubtedly 
such  as  must  have  grown  on  land,  do  not  prove  that  the  bed 
in  which  they  occur  was  formed  on  land.  Many  of  the  remains 
of  plants  known  to  us  are  extraneous  to  the  bed  in  which  they 
are  now  found,  having  reached  their  present  site  by  falling  into 
lakes  or  rivers,  or  being  carried  out  to  sea  by  floods  or  gales  of 
wind.  There  are,  however,  many  cases  in  which  plants  have 
undoubtedly  grown  on  the  very  spot  where  we  now  find  them. 
Thus  it  is  now  generally  admitted  that  the  great  coal-fields 
of  the  Carboniferous  age  are  the  result  of  the  growth  in  situ 
of  the  plants  which  compose  coal,  and  that  these  grew  on  vast 
marshy  or  partially  submerged 
tracts  of  level  alluvial  land., 
We  have,  however,  distinct 
evidence  of  old  land-surfaces, 
both  in  the  Coal-measures  and 
in  other  cases  (as,  for  in- 
stance, in  the  well-known 
"dirt-bed"  of  the  Purbeck 
seri'es).  When,  for  example, 
we  find  the  erect  stumps  of 
trees  standing  at  right  angles 
to  the  surrounding  strata,  we 
know  that  the  surface  through 
which  these  send  their  roots 
was  at  one  time  the  surface  of 
the  dry  land,  or  in  other 
words,  was  an  ancient  soil 
(fig.  19). 

In  many  cases  fossils  en- 
able us  to  come  to  important 
conclusions  as  to  the  climate 
of  the  period  in  which  they 

lived,  but  only  a  few  in-  FIR.  19,-ErectTree containing  Reptilian 
stances  of  this  can  be  here  remains.  Coal-measures,  Nova  Scotia, 
adduced.  As  fossils  in  the 


56  PRINCIPLES  OF  PALAEONTOLOGY. 

majority  of  instances  are  the  remains  of  marine  animals,  it  is 
mostly  the  temperature  of  the  sea  which  can  alone  be  determined 
in  this  way;  and  it  is  important  to  remember  that,  owing  to  the 
existence  of  heated  currents,  the  marine  climate  of  a  given  area 
does  not  necessarily  imply  a  correspondingly  warm  climate  in 
the  neighboring  land.  Land-climates  can  only  be  determined  by 
the  remains  of  land-animals  or  land-plants,  and  these  are  com- 
paratively rare  as  fossils.  It  is  also  important  to  remember  that  all 
conclusions  on  this  head  are  really  based  upon  the  present  dis- 
tribution of  animal  and  vegetable  life  on  the  globe,  and  are 
therefore  liable  to  be  vitiated  by  the  following  considerations : — 

a.  Most  fossils  are  extinct,   and  it  is  not  certain  that  the 
habits    and    requirements    of    any    extinct   animal    were    exactly 
similar  to  those  of  its  nearest  living  relative. 

b.  When  we  get  very  far  back  in  time,  we  meet  with  groups 
of  organisms  so  unlike  anything  we  know  at  the  present  day  as 
to  render  all  conjectures  as  to  climate   found  upon  their  sup- 
posed habits  more  or  less  uncertain  and  unsafe. 

c.  In  the  case  of  marine  animals,  we  are  as  yet  very  far 
from  knowing  the  exact  limits  of  distribution  of  many  species 
within  our  present  seas ;  so  that  conclusions  drawn  from  living 
forms   as   to   extinct   species    are   apt   to   prove   incorrect.     For 
instance,  it  has  recently  been  shown  that  many  shells  formerly 
believed  to  be  confined  to  the  Arctic  Seas  have,  by  reason  of  the 
extension   of   Polar  currents,   a  wide   range  to  the   south ;   and. 
this  has  thrown  doubt  upon  the  conclusions  drawn  from  fossil 
shells  as  to  the  Arctic  conditions  under  which  certain  beds  were 
supposed  to  have  been  deposited. 

d.  The  distribution  of  animals  at  the  present  day  is  certainly 
dependent    upon    other    conditions    beside    climate    alone ;    and 
the   causes   which   now   limit   the    range   of    given    animals    are 
certainly  such  as  belong  to  the  existing  order  of  things.     But 
the  establishment  of  the  present  order  of  things  does  not  date 
back  in  many  cases  to  the  introduction  of  the  present  species  of 
animals.      Even    in    the    case    therefore,    of    existing    species    of 
animals,  it  can  often  be  shown  that  the  past  distribution  of  the 
species  was  different  formerly  to  what  it  is  now,  not  necessarily 
because  the  climate  has  changed,  but  because  of  the  alteration 
of  other  conditions  essential  to  the  life  of  the  species  of  con- 
ducing to  its  extension. 

Still,  we  are  in  many  cases  able  to  draw  completely  reliable 
conclusions  as  to  the  climate  of  a  given  geological  period,  by 
an  examination  of  the  fossils  belonging  to  that  period.  Among 


CONCLUSIONS  TO  BE  DRAWN  FROM  FOSSILS.     57 

the  more  striking  examples  of  how  the  past  climate  of  a  region 
may  be  deduced  from  the  study  of  the  organic  remains  con- 
tained in  its  rocks,  the  following  may  be  mentioned:  It  has 
been  shown  that  in  Eocene  times,  or  at  the  commencement 
of  the  Tertiary  period,  the  climate  of  what  is  now  Western 
Europe  was  of  a  tropical  or  sub-tropical  character.  Thus  the 
Eocene  beds  are  found  to  contain  the  remains  of  shells  such 
as  now  inhabit  tropical  seas,  as,  for  example,  Cowries  and 
Volutes;  and  with  these  are  the  fruits  of  palms,  and  the 
remains  of  other  tropical  plants.  It  has  been  shown,  again, 
that  in  Miocene  times,  or  about  the  middle  of  the  Tertiary 
period,  Central  Europe  was  peopled  with  a*  luxuriant  flora 
resembling  that  of  the  warmer  parts  of  the  United  States,  and 
leading  to  the  conclusion  that  the  mean  annual  temperature 
must  have  been  at  least  30°  hotter  than  it  is  at  present.  It 
has  been  shown  that,  at  the  same  time,  Greenland,  now  buried 
beneath  a  vast  ice-shroud,  was  warm  enough  to  support  a  large 
number  of  trees,  shrubs,  and  other  plants,  such  as  inhabit  the 
temperate  regions  of  the  globe.  Lastly,  it  has  been  shown, 
upon  physical  as  well  as  palaeontological  evidence,  that  the 
greater  part  of  the  North  Temperate  Zone,  at  a  comparatively 
recent  geological  period,  has  been  visited  with  all  the  rigors 
of  an  Arctic  climate,  resembling  that  of  Greenland  at  the  pres- 
ent day.  This  is  indicated  by  the  occurrence  of  Arctic  shells 
in  the  superficial  deposits  of  this  period,  whilst  the  Musk-ox 
and  the  Reindeer  roamed  far  south  of  their  present  limits. 

Lastly,  it  was  from  the  study  of  fossils  that  geologists  learnt 
originally  to  comprehend  a  fact  which  may  be  regarded  as  of 
cardinal  importance  in  all  modern  geological  theories  and 
speculations — namely,  that  the  crust  of  earth  is  liable  to 
local  elevations  and  subsidences.  For  long  after  the  remains 
of  shells  and  other  marine  animals  were  for  the  first  time  ob- 
served in  the  solid  rocks  forming  the  dry  land,  and  at  great 
heights  above  the  sea-level,  attempts  were  made  to  explain  this 
almost  unintelligible  phenomenon  upon  the  hypothesis  that 
the  fossils  in  question  were  not  really  the  objects  they  repre- 
sented, but  were  in  truth  mere  lusus  naturce,  due  to  some 
"  plastic  virtue  latent  in  the  earth. "  The  common-sense  of 
scientific  men,  'however,  soon  rejected  this  idea,  and  it  was 
agreed  by  universal  consent  that  these  bodies  really  were  the 
remains  of  animals  which  formerly  lived  in  the  sea.  When 
once  this  was  admitted,  the  further  steps  were  comparatively 
easy,  and  at  the  present  day  no  geological  doctrine  stands  on 


58  PRINCIPLES  OF  PALAEONTOLOGY. 

a  firmer  basis  than  that  which  teaches  us  that  our  present  con- 
tinents and  islands,  fixed  and  immovable  as  they  appear,  have 
been  repeatedly  sunk  beneath  the  ocean. 


CHAPTER  VI 
THE  BIOLOGICAL  RELATIONS  OF  FOSSILS. 

Not  only  have  fossils,  as  we  have  seen,  a  most  important 
bearing  upon  the  sciences  of  Geology  and  Physical  Geography, 
but  they  have  relations  of  the  most  complicated  and  weighty 
character  with  the  numerous  problems  connected  with  the 
study  of  living  beings,  or  in  other  words,  with  the  science  of 
Biology.  To  such  an  extent  is  this  the  case,  that  no  adequate 
comprehension  of  Zoology  and  Botany,  in  their  modern  form, 
is  so  much  as  possible  without  some  acquaintance  with  the 
types  of  animals  and  plants  which  have  passed  away.  There 
are  also  numerous  speculative  questions  in  the  domain  of  vital 
science,  which,  if  soluble  at  all,  can  only  hope  to  find  their  key 
in  researches  carried  out  on  extinct  organisms.  To  discuss 
fully  the  biological  relations  of  fossils  would,  therefore,  afford 
matter  for  a  separate  treatise;  and  all  that  can  be  done  here  "is 
to  indicate  very  cursorily  the  principal  points  to  which  the 
attention  of  the  palseontological  student  ought  to  be  directed. 

In  the  first  place,  the  great  majority  of  fossil  animals  and 
plants  are  "  extinct " — that  is  to  say,  they  belong  to  species 
which  are  no  longer  in  existence  at  the  present  day.  So  far, 
however,  from  there  being  any  truth  in  the  old  view  that  there 
were  periodic  destructions  of  all  the  living  beings  in  existence 
upon  the  earth,  followed  by  a  corresponding  number  of  new 
creations  of  animals  and  plants,  the  actual  facts  of  the  case  show 
that  the  extinction  of  old  forms  and  the  introduction  of  nevr 
forms  have  been  processes  constantly  going  on  throughout  the 
whole  of  geological  time.  Every  species  seems  to  come  into 
being  at  a  certain  definite  point  of  time,  and  to  finally  disappear 
at  another  definite  point ;  though  there  are  few  instances 
indeed,  if  there  are  any,  in  which  our  present  knowledge  would 
permit  us  safely  to  fix  with  precision  the  times  of  entrance  and 
exit.  There  are,  moreover,  marked  differences  in  the  actual 
time  during  which  different  species  remained  in  existence,  and 


THE  BIOLOGICAL  RELATIONS  OF  FOSSILS,        59 

therefore  corresponding  differences  in  their  "vertical  range"  or, 
in  other  words,  in  the  actual  amount  and  thickness  of  strata 
through  which  they  present  themselves  as  fossils.  Some  species 
are  found  to  range  through  two  or  even  three  formations,  and 
a  few  have  an  even  more  extended  life.  More  commonly  the 
species  which  begin  in  the  commencement  of  a  great  forma- 
tion die  out  at  or  before  its  close,  whilst  those  which  are 
introduced  for  the  first  time  near  the  middle  or  end  of  the 
formation  may  either  become  extinct,  or  may  pass  on  into  the 
next  succeeding  formation.  As  a  general  rule,  it  is  the  animals 
which  have  the  lowest  and  simplest  organization  that  have  the 
longest  range  in  time,  and  the  additional  possession  of  micro- 
scopic or  minute  dimensions  seems  also  to  favor  longevity. 
Thus  some  of  the  Foraminifera  appear  to  have  survived,  with 
little  or  no  perceptible  alteration,  from  the  Silurian  period  to 
the  present  day;  whereas  large  and  highly-organized  animals, 
though  long-lived  as  individuals,  rarely  seem  to  live  long  speci- 
fically, and  have,  therefore,  usually  a  restricted  vertical  range. 
Exceptions  to  this,  however  are  occasionally  to  be  found  in 
some  "  persistent  types, "  which  extend  through  a  succession  of 
geological  periods  with  very  little  modification.  Thus  the  ex- 
isting Lampshells  of  the  genus  Lingula  are  little  changed  from 
the  Lingula  which  swarmed  in  the  Lower  Silurian  seas;  and 
the  existing  Pearly  Nautilus  is  the  last  descendant  of  a  clan 
nearly  as  ancient.  On  the  other  hand,  some  forms  are  singu- 
larly restricted  in  their  limits,  and  seem  to  have  enjoyed  a 
comparatively  brief  lease  of  life.  An  example  of  this  is  to 
be  found  in  many  of  the  Ammonites — close  allies  of  the  Nau- 
tilus— which  are  often  confined  strictly  to  certain  zones  of  strata, 
in  some  cases  of  very  insignificant  thickness. 

Of  the  causes  of  extinction  amongst  fossil  animals  and 
plants,  we  know  little  or  nothing.  All  we  can  say  is,  that  the 
attributes  which  constitute  a  species  do  not  seem  to  be  intrin- 
sically endowed  with  permanence,  any  more  than  the  attributes 
which  constitute  an  individual,  though  the  former  may  endure 
whilst  many  successive  generations  of  the  latter  have  dis- 
appeared. Each  species  appears  to  have  its  own  life-period, 
its  commencement,  its  culmination,  and  its  gradual  decay ;  and  the 
life-periods  of  different  species  may  be  of  very  different 
duration. 

From  what  has  been  said  above,  it  may  be  gathered  that 
our  existing  species  of  animals  and  plants  are,  for  the  most 
part,  quite  of  modern  origin,  using  the  term  "  modern "  in  its 


6o  PRINCIPLES  OF  PALEONTOLOGY. 

geological  acceptation.  Measured  by  human  standards,  the 
majority  of  existing  animals  (which  are  capable  of  being 
preserved  as  fossils)  are  known  to  have  a  high  antiquity;  and 
some  of  them  can  boast  of  a  pedigree  which  even  the  geologist 
may  regard  with  respect.  Not  a  few  of  our  shell-fish  are  known 
to  have  commenced  their  existence  at  some  point  of  the 
Tertiary  period;  one  Lampshell  (Terebratulina  caput-serpentis} 
is  believed  to  have  survived  since  the  Chalk;  and  some  of  the 
Foraminifera  date,  at  any  rate,  from  the  Carboniferous  period. 
We  learn  from  this  the  additional  fact  that  our  existing  animals 
and  plants  do  not  constitute  an  assemblage  of  organic  forms 
which  were  introduced  into  the  world  collectively  and  simul- 
taneously, but  that  they  commenced  their  existence  at  very 
different  periods,  some  being  extremely  old,  whilst  others  may 
be  regarded  as  comparatively  recent  animals.  And  this  intro- 
duction of  the  existing  fauna  and  flora  was  a  slow  and  gradual 
process,  as  shown  admirably  by  the  study  of  the  fossil  shells 
of  the  Tertiary  period.  Thus,  in  the  earlier  Tertiary  period, 
we  find  about  95  per  cent  of  the  known  fossil  shells  to  be  species 
that  are  no  longer  in  existence,  the  remaining  5  per  cent  being 
forms  which  are  known  to  live  in  our  present  seas.  In  the 
middle  of  the  Tertiary  period  we  find  many  more  recent  and 
still  existing  species  of  shells,  and  the  extinct  types  are  much 
fewer  in  number ;  and  this  gradual  introduction  of  forms  now 
living  goes  on  steadily,  till,  at  the  close  of  the  Tertiary  period, 
the  proportions  with  which  we  started  may  be  reversed,  as 
many  as  90  or  95  per  cent  of  the  fossil  shells  being  forms  still 
alive,  while  not  more  than  5  per  cent  may  have  disappeared. 

All  known  animals  at  the  present  day  may  be  divided  into 
some  five  or  six  primary  divisions,  which  are  known  technically 
as  "  sub-kingdoms. "  Each  of  these  sub-kingdoms  *  may  be 
regarded  as  representing  a  certain  type  or  plan  of  structure, 
and  all  the  animals  comprised  in  each  are  merely  modified  forms 
of  this  common  type.  Not  only  are  all  known  living  animals 
thus  reducible  to  some  five  or  six  fundamental  plans  of  struc- 
ture, but  amongst  the  vast  series  of  fossil  forms  no  one  has 
yet  been  found — however  unlike  any  existing  animal — to  possess 
peculiarities  which  would  entitle  it  to  be  placed  in  a  new  sub- 
kingdom.  All  fossil  animals,  therefore,  are  capable  of  being 
referred  to  one  or  other  of  the  primary  divisions  of  the  animal 
kingdom.  Many  fossil  groups  have  no  closely-related  group 

*  In  the  Appendix  a  brief  definition  is  given  of  the  sub-kingdoms,  and 
the  chief  divisions  of  each  are  enumerated. 


THE  BIOLOGICAL  RELATIONS  OF  FOSSILS,        61 

now  in  existence ;  but  in  no  case  do  we  meet  with  any  grand 
structural  type  which  has  not  survived  to  the  present  day. 

The  old  types  of  life  differ  in  many  respects  from  those  now 
upon  the  earth ;  and  the  further  back  we  pass  in  time,  the 
more  marked  does  this  divergence  become.  Thus,  if  we  were 
to  compare  the  animals  which  lived  in  the  Silurian  seas  with 
those  inhabiting  our  present  oceans,  we  should  in  most  in- 
stances find  differences  so  great  as  almost  to  place  us  in 
another  world.  This  divergence  is  the  most  marked  in  the 
Palaeozoic  forms  of  life,  less  so  in  those  of  the  Mesozoic  period, 
and  less  still  in  the  Tertiary  period.  Each  successive  formation 
has  therefore  presented  us  with  animals  becoming  gradually 
more  and  more  like  those  now  in  existence ;  and  though  there 
is  an  immense  and  striking  difference  between  the  Silurian  ani- 
mals and  those  of  to-day,  this  difference  is  greatly  reduced  if 
we  compare  the  Silurian  fauna  with  the  Devonian;  that  again 
with  the  Carboniferous ;  and  so  on  till  we  reach  the  present. 

It  follows  from  the  above  that  the  animals  of  any  given 
formation  are  more  like  those  of  the  next  formation  below, 
and  of  the  next  formation  above,  than  they  are  to  any  others; 
and  this  fact  of  itself  is  an  almost  inexplicable  one,  unless  we 
believe  that  the  animals  of  any  given  formation  are,  in  part  at 
any  rate,  the  lineal  descendants  of  the  animals  of  the  preced- 
ing formation,  and  the  progenitors,  also  in  part  at  least,  of  the 
animals  of  the  succeeding  formation.  In  fact,  the  palaeon- 
tologist is  so  commonly  confronted  with  the  phenomenon  of 
closely-allied  forms  of  animal  life  succeeding  one  another  in 
point  of  time,  that  he  is  compelled  to  believe  that  such  forms 
have  been  developed  from  some  common  ancestral  type  by 
some  process  of  "  evolution. "  On  the  other  hand,  there  are 
many  phenomena,  such  as  the  apparently  sudden  introduction 
of  new  forms  throughout  all  past  time,  and  the  common  occur- 
rence of  wholly  isolated  types,  which  cannot  be  explained  in 
this  way.  Whilst  it  seems  certain,  therefore,  that  many  of  the 
phenomena  of  the  succession  of  animal  life  in  past  periods  can 
only  be  explained  by  some  law  of  evolution,  it  seems  at  the 
same  time  certain  that  there  has  always  been  some  other 
deeper  and  higher  law  at  work,  on  the  nature  of  which  it 
would  be  futile  to  speculate  at  present. 

Not  only  do  we  find  that  the  animals  of  each  successive 
formation  become  gradually  more  and  more  like  those  now 
existing  upon  the  globe,  as  we  pass  from  the  older  rocks  into 
the  newer,  but  we  also  find  that  there  has  been  a  gradual  pro- 


62  PRINCIPLES  OF  PALEONTOLOGY. 

gression  and  development  in  the  types  of  animal  life  which 
characterize  the  geological  ages.  If  we  take  the  earliest-known 
and  the  oldest  examples  of  any  given  group  of  animals,  it  can 
sometimes  be  shown  that  these  primitive  forms,  though  in 
themselves  highly  organized,  possessed  certain  characters  such 
as  are  now  only  seen  in  the  young  of  their  existing  representa- 
tives. In  technical  language,  the  early  forms  of  life  in  some 
instances  possess  "  embryonic "  characters,  though  this  does 
not  prevent  them  often  attaining  a  size  much  more  gigantic 
than  their  nearest  living  relatives.  Moreover,  the  ancient  forms 
of  life  are  often  what  is  called  "  comprehensive  types  " — that 
is  to  say,  they  possess  characters  in  combination  such  as  we 
nowadays  only  find  separately  developed  in  different  groups  of 
animals.  Now,  this  permanent  retention  of  embryonic  char- 
acters and  this  "  comprehensiveness  "  of  structural  type  are  signs 
of  what  a  zoologist  considers  to  be  a  comparatively  low  grade  of 
organization ;  and  the  prevalence  of  these  features  in  the  earlier 
forms  of  animals  is  a  very  striking  phenomenon,  though  they 
are  none  the  less  perfectly  organized  so  far  as  their  own  type 
is  concerned.  As  we  pass  upwards  in  the  geological  scale,  we 
find  that  these  features  gradually  disappear,  higher  and  ever 
higher  forms  are  introduced,  and  "  specialization  "  of  type  takes 
the  place  of  the  former  comprehensiveness.  We  shall  have 
occasion  to  notice  many  of  the  facts  on  which  these  views  are 
based  at  a  later  period,  and  in  connection  with  actual  examples. 
In  the  meanwhile,  it  is  sufficient  to  state,  as  a  widely-accepted 
generalization  of  palaeontology,  that  there  has  been  in  the  past 
a  general  progression  of  organic  types,  and  that  the  appearance 
of  the  lower  forms  of  life  has  in  the  main  preceded  that  of 
the  higher  forms  in  point  of  time. 


PART      II. 


HISTORICAL  PALEONTOLOGY. 


PART     II. 


CHAPTER  VII. 
THE  LAURENTIAN  AND  HURON  I  AN  PERIODS. 

The  Laurentian  Rocks  constitute  the  base  of  the  entire  strati- 
fied series,  and  are,  therefore,  the  oldest  sediments  of  which 
we  have  as  yet  any  knowledge.  They  are  more  largely  and 
more  typically  developed  in  North  America,  and  especially  in 
Canada,  than  in  any  known  part  of  the  world,  and  they  derive 
their  title  from  the  range  of  hills  which  the  old  French  geog- 
raphers named  the  "  Laurentides. "  These  hills  are  com- 
posed of  Laurentian  Rocks,  and  form  the  watershed  between 
the  valley  of  the  St  Lawrence  river  on  the  one  hand,  and  the 
great  plains  which  stretch  northwards  to  Hudson  Bay  on  the 
other  hand.  The  main  area  of  these  ancient  deposits  forms 
a  great  belt  of  rugged  and  undulating  country,  which  extends 
from  Labrador  westwards  to  Lake  Superior,  and  then  bends 
northwards  towards  the  Arctic  Sea.  Throughout  this  extensive 
area  the  Laurentian  Rocks  for  the  most  part  present  themselves 
in  the  form  of  low,  rounded,  ice-worn  hills,  which,  if  generally 
wanting  in  actual  sublimity,  have  a  certain  geological  grandeur 
from  the  fact  that  they  "  have  endured  the  battles  and  the  storms 
of  time  longer  than  any  other  mountains"  (Dawson).  In  some 
places,  however,  the  Laurentian  Rocks  produce  scenery  of  the 
most  magnificent  character,  as  in  the  great  gorge  cut  through 
them  by  the  river  Saguenay,  where  they  rise  at  times  into  verti- 
cal precipices  1500  feet  in  height.  In  the  famous  group  of 
the  Adirondack  mountains,  also,  in  the  state  of  New  York 
they  form  elevations  no  less  than  6000  feet  above  the  level  of 
the  sea.  As  a  general  rule,  the  character  of  the  Laurentian 
region  is  that  of  a  rugged,  rocky,  rolling  country,  often  densely 
timbered,  but  rarely  well  fitted  for  agriculture,  and  chiefly 
attractive  to  the  hunter  and  the  miner. 

As  regards  its  mineral  characters,  the  Laurentian  series  is 

5  65 


66  HISTORICAL  PALAEONTOLOGY. 

composed  throughout  of  metamorphic  and  highly  crystalline 
rocks,  which  are  in  a  high  degree  crumpled,  folded,  and  faulted. 
By  the  late  Sir  William  Logan  the  entire  series  was  divided 
into  two  great  groups,  the  Lower  Laurentian  and  the  Upper 
Laurentian,  of  which  the  latter  rests  unconformably  upon  the 
truncated  edges  of  the  former,  and  is  in  turn  unconformably 
overlaid  by  strata  of  Huronian  and  Cambrian  age  (fig.  20). 

The  Lozver  Laurentian  series  attains  the  enormous  thickness 
of  over  20,000  feet,  and  is  composed  mainly  of  great  beds  of 
gneiss,  altered  sandstones  (quartzites),  mica-schist,  hornblende- 
schist,  magnetic  iron-ore,  and  haematite,  together  with  masses  of 
limestone.  The  limestones  are  especially  interesting,  and  have  an 


Fig.  20— Diagrammatic  section  of  the  Laurentian  Rocks  In  LowerCanada.  a  Lower 
Laurentian;  6  Upper  Laurentian,  resting  unconformably  upon  the  lower  series;  cCam- 
brian  strata  (Potsdam  Sandstone),  resting  unconformably  on  the  Upper  Laurentian. 

extraordinary  development — three  principal  beds  being  known, 
of  which  one  is  not  less  than  1500  feet  thick;  the  collective 
thickness  of  the  whole  being  about  3500  feet. 

The  Upper  Laurentian  series,  as  before  said,  reposes  uncon- 
formably upon  the  Lower  Laurentian,  and  attains  a  thickness 
of  at  least  10,000  feet.  Like  the  preceding,  it  is  wholly  meta- 
morphic, and  is  composed  partly  of  masses  of  gneiss  and  quartz- 
ite;  but  it  is  especially  distinguished  by  the  possession  of  great 
beds  of  felspathic  rock,  consisting  principally  of  "Labrador 
felspar. " 

Though  typically  developed  in  the  great  Canadian  area 
already  spoken  of,  the  Laurentian  Rocks  occur  in  other  localities, 
both  in  America  and  in  the  Old  World.  In  Britain,  the  so- 
called  "  fundamental  gneiss "  of  the  Hebrides  and  of  Suther- 
landshire  is  probably  of  Lower  Laurentian  age,  and  the  "  hy- 
persthene  rocks "  of  the  Isle  of  Syke  may,  with  great  proba- 
bility, be  regarded  as  referable  to  the  Upper  Laurentian.  In 
other  localities  in  Great  Britain  (as  in  St.  David's,  South 
Wales;  the  Malvern  Hills;  and  the  North  of  Ireland)  occur 
ancient  metamorphic  deposits  which  also  are  probably  refer- 
able to  the  Laurentian  series.  The  so-called  "  primitive  gneiss " 
of  Norway  appears  to  belong  to  the  Laurentian,  and  the 
ancient  metamorphic  rocks  of  Bohemia  and  Bavaria  may  be 
regarded  as  being  approximately  of  the  same  age. 

By   some   geological   writers   the   ancient   and   highly   meta- 


THE  LAURENTIAN  AND  HURONIAN  PERIODS.     67 

morphosed  sediments  of  the  Laurentian  and  the  succeeding 
Huronian  series  have  been  spoken  of  as  the  "  Azoic  rocks " 
(Gr.  a,  without;  zoe,  life)  ;  but  even  if  we  were  wholly  destitute 
of  any  evidence  of  life  during  these  periods,  this  name  would  be 
objectionable  upon  theoretical  grounds.  If  a  general  name  be 
needed,  that  of  "  Eozoic "  (Gr.  eos,  dawn;  zoe,  life),  proposed 
by  Principal  Dawson,  is  the  most  appropriate.  Owing  to  their 
metamorphic  condition,  geologists  long  despaired  of  ever  de- 
tecting any  traces  of  life  in  the  vast  pile  of  strata  which  con- 
stitute the  Laurentian  System.  Even  before  any  direct  traces 
were  discovered,  it  was,  however,  pointed  out  that  there  were 
good  reasons  for  believing  that  the  Laurentian  seas  had  been 
tenanted  by  an  abundance  of  living  beings.  These  reasons 
are  briefly  as  follows: — (i)  Firs'tly,  the  Laurentian  series  con- 
sists, beyond  question,  of  marine  sediments  which  originally 
differed  in  no  essential  respect  from  those  which  were  subse- 
quently laid  down  in  the  Cambrian  or  Silurian  periods.  (2) 
In  all  formations  later  than  the  Laurentian,  any  limestones 
which  are  present  can  be  shown,  with  few  exceptions,  to  be 
organic  rocks,  and  to  be  more  or  less  largely  made  up  of  the 
comminuted  debris  of  marine  or  fresh-water  animals.  The 
Laurentian  limestones,  in  consequence  of  the  metamorphism 
to  which  they  have  been  subjected,  are  so  highly  crystalline 
(fig.  21 )  that  the  microscope  fails  to  detect  any  organic  struc- 
ture in  the  rock,  and  no  fos- 
sils beyond  those  which  will 
be  spoken  of  immediately  have 
as  yet  been  discovered  in 
them.  We  know,  however,  of 
numerous  cases  in  which  lime- 
stones, of  later  age,  and  un- 
doubtedly organic  to  begin 
with,  have  been  rendered  so 
intensely  crystalline  by  meta- 
morphic action  that  all  traces 
of  organic  structure  have  been 
obliterated.  We  have  there- 
fore, by  analogy,  the  strongest  „,.  2l.-Sectlon  of  Lower  Laurentian 
possible  ground  for  believing  Limestone  from  Hull,  Ottawa;  enlarged 
,  ,  1  ,  r  T  '  five  diameters.  The  rock  is  very  highly 

that  the  vast  beds  of  Lauren-  crystalline,  and  contains  mica  and  other 
tion  UmAcf^tiA  Jiowo  Kooti  ^t-Irr  minerals.  The  irregular  black  masses  in 
tian  limestone  have  been  orig-  n  are  graphite.  (Original.) 

inally   organic   in   their   origin, 

and  primitively  composed,  in  the  main,  of  the  calcareous  skele- 


68  HISTORICAL  PALAEONTOLOGY. 

tons  of  marine  animals.  It  would,  in  fact,  be  a  matter  of 
great  difficulty  to  account  for  the  formation  of  these  great  cal- 
careous masses  on  any  other  hypothesis.  (3)  The  occurrences  of 
phosphate  of  lime  in  the  Laurentian  Rocks  in  great  abundance, 
and  sometimes  in  the  form  of  irregular  beds,  may  very  possibly 
be  connected  with  the  former  existence  in  the  strata  of  the  re- 
mains of  marine  animals  of  whose  skeletons  this  mineral  is  a  con- 
stituent. (4)  The  Laurentian  Rocks  contain  a  vast  amount  of 
carbon  in  the  form  of  black-lead  or  graphite.  This  mineral  is 
especially  abundant  in  the  limestones,  occurring  in  regular  beds, 
in  veins  or  strings,  or  disseminated  through  the  body  of  the  lime- 
stone in  shape  of  crystals,  scales,  or  irregular  masses.  The 
amount  of  graphite  in  some  parts  of  the  Lower  Laurentian  is 
so  great  that  it  has  been  calculated  as  equal  to  the  quantity  of 
carbon  present  in  an  equal  thickness  of  the  Coal-measures. 
The  general  source  of  solid  carbon  in  the  crust  of  the  earth 
is,  however,  plant-life;  and  it  seems  impossible  to  account  for 
the  Laurentian  graphite,  except  upon  the  supposition  that  it 
is  metamorphosed  vegetable  matter.  (5)  Lastly,  the  great 
beds  of  iron-ore  (peroxide  and  magnetic  oxide)  which  occur 
in  the  Laurentian  series  interstratified  with  the  other  rocks, 
point  with  great  probability  to  the  action  of  vegetable  lif  e  ; 
since  similar  deposits  in  later  formations  can  commonly  be 
shown  to  have  been  formed  by  the  deoxidizing  power  of  vege- 
table matter  in  a  state  of  decay. 

In  the  words  of  Principal  Dawson,  "  any  one  of  these  rea- 
sons might,  in  itself,  be  held  insufficient  to  prove  so  great  and, 
at  first  sight,  unlikely  a  conclusion  as  that  of  the  existence  of 
abundant  animal  and  vegetable  life  in  the  Laurentian;  but  the 
concurrence  of  the  whole  in  a  series  of  deposits  unquestion- 
ably marine,  forms  a  chain  of  evidence  so  powerful  that  it 
might  command  belief  even  if  no  fragment  of  any  organic  or 
living  form  or  structure  had  ever  been  recognized  in  these  an- 
cient rocks. "  Of  late  years,  however,  there  have  been  dis- 
covered in  the  Laurentian  Rocks  certain  bodies  which  are 
believed  to  be  truly  the  remains  of  animals,  and  of  which  by 
far  the  most  important  is  the  structure  known  under  the  now 
celebrated  name  of  Eozo'dn.  If  truly  organic,  a  very  special 
and  exceptional  interest  attaches  itself  toEozoon,  as  being  the 
most  ancient  fossil  animal  of  which  we  have  any  knowledge; 
but  there  are  some  who  regard  it  really  a  peculiar  form  of 
mineral  structure,  and  a  severe,  protracted,  and  still  unfinished 
controversy  has  been  carried  on  as  to  its  nature.  Into  this 


THE  LAURENTIAN  AND  HURONIAN  PERIODS.     69 

controversy  it  is  wholly  unnecessary  to  enter  here ;  and  it  will 
be  sufficient  to  briefly  explain  the  structure  of  Eozo'on,  as  eluci- 
dated by  the  elaborate  and  masterly  investigations  of  Car- 
penter and  Dawson,  from  the  standpoint  that  it  is  a  genuine 
organism — the  balance  of  evidence  up  to  this  moment  inclin- 
ing decisively  to  this  view. 

The  structure  known  as  Eozo'dn  is  found  in  various  localities 
in  the  Lower  Laurentian  limestones  of  Canada,  in  the  form  of 
isolated  masses  or  spreading  layers,  which  are  composed  of 
thin  alternating  laminae,  arranged  more  or  less  concentrically 
(fig.  22).  The  laminae  of  these  masses  are  usually  of  different 


Fig.  22.— Fragment  of  Eozoon,  of  the  natural  size,  showing  alternate  laminae 
of  loganlte  and  dolomite.    (After  Dawson.) 

colors  and  composition;  one  series  being  white,  and  composed 
of  carbonate  of  lime — whilst  the  laminae  of  the  second  series 
alternate  with  the  preceding,  are  green  in  color,  and  are  found 
by  chemical  analysis  to  consist  of  some  silicate,  generally  ser- 
pentine or  the  closely-related  "  loganite. "  In  some  instances, 
however,  all  the  laminae  are  calcareous,  the  concentric  arrange- 
ment still  remaining  visible  in  consequence  of  the  fact  that 
the  laminae  are  composed  alternately  of  lighter  and  darker 
colored  limestone. 

When  first  discovered,  the  masses  of  Eozo'dn  were  supposed 
to  be  of  a  mineral  nature;  but  their  striking  general  resem- 
blance to  the  undoubted  fossils  which  will  be  subsequently 
spoken  of  under  the  name  of  Stromatopora  was  recognized  by 
Sir  William  Logan,  and  specimens  were  submitted  for  minute 
examination,  first  to  Principal  Dawson,  and  subsequently  to 
Dr.  W.  B.  Carpenter.  After  a  careful  microscopic  examina- 
tion, these  two  distinguished  observers  came  to  the  conclusion 
that  Eozoon  was  truly  organic,  and  in  this  opinion  they  were 


70 


HISTORICAL  PALEONTOLOGY. 


li^ife1 «•"''• " ."^••5 


afterwards  corroborated  by  other  high  authorities  (Mr.  W.  K. 
Parker,  Professor  Rupert  Jones,  Mr.  H.  B.  Brady,  Professor 
Giimbel,  &c.)  Stated  briefly,  the  structure  of  Eosoon,  as  ex- 
hibited by  the  microscope,  is  as  follows: — 

The   concentrically-laminated  mass   of  Eozo'dn  is   composed 
of  numerous  calcareous  layers,  representing  the  original  skele- 
ton of  the  organism  (fig.  23,  b).     These  calcareous  layers  serve 
to    separate    and    de- 
fine a  series  of  cham- 
bers arranged  in  sue-  £>- „. '...,. "•••...•••—•..^^ 

cessive  tiers,  one 
above  the  other  (fig. 
23,  A,  B ,  C)  ;  and 
they  are  perforated 
not  only  by  passages 
(fig.  23,  c),  which 
serve  to  place  suc- 
cessive tiers  of  cham- 
bers in  communica- 
tion, but  also  by  a 
system  of  delicate 

branching    canals  (fig. 

Fig.  23.— Diagram  of  a  portion  of  Eozoon  cut  verti- 

23,    d),  Moreover,    cally.    A,  B,  C,  Three  tiers  of  chambers  communicating 

tViA    ^ntral    onrl    r\rin      with  one  another  by  slightly  constructed  apertures:  a  a, 

~    The  true  shell-wall,  perforated  by  numerous  delicate 

cipal    portion    of    each    tubes;  &  6,  The  main  calcareous  skeleton  ("intermedi- 
ate skeleton");  c,  Passage  of  communication  ("stolon- 

calcareous  layer,  With  passage")  from  one  tier  of  chambers  to  another;  d, 
.1,  '£.  A  1  Ramifying  tubes  in  the  calcareous  skeleton.  (After 

canal-    Carpenter.)      . 
system     just     spoken 

of,  is  bound  both  above  and  below  by  a  thin  lamina  which  has 
a  structure  of  its  own,  and  which  may  be  regarded  as  the  proper 
shell-wall  (fig.  23,  a  a}.  This  proper  wall  forms  the  actual  lin- 
ing of  the  chambers,  as  well  as  the  outer  surface  of  the  whole 
mass;  and  it  is  perforated  with  numerous  fine  vertical  tubes 
(fig.  24,  a  a),  opening  into  the  chambers  and  on  to  the  sur- 
face by  corresponding  fine  pores.  From  the  resemblance  of 
this  tubulated  layer  to  similar  structures  in  the  shell  of  the 
Nummulite,  it  is  often  spoken  of  as  the  "  Nummuline  layer. " 
The  chambers  are  sometimes  piled  up  one  above  the  other  in 
an  irregular  manner ;  but  they  are  more  commonly  arranged 
in  regular  tiers,  the  separate  chambers  being  marked  off  from 
one  another  by  projections  of  the  wall  in  the  form  of  parti- 
tions, which  are  so  far  imperfect  as  to  allow  of  a  free  communi- 
cation between  contiguous  chambers.  In  the  original  condition 


THE  LAURENTIAN  AND  HURONIAN  PERIODS.     71 

of  the  organism,  all  these  chambers,  of  course,  must  have 
been  filled  with  living  matter ;  but  they  are  found  in  the  present 
state  of  the  fossil  to  be  generally  filled  with  some  silicate,  such 
as  serpentine,  which  not  only  fills  the  actual  chambers,  but  has 


Fig,  24.— Portion  of  one  of  the  calcareous  layers  of  Eozoon,  magnified  100  diameters, 
a  a,  The  proper  wall  ("Nummuline  layer")  of  one  of  the  chambers,  showing  the  fine 
vertical  tubuli  with  which  it  is  penetrated,  and  which  are  slightly  bent  along  the  line 
a'  «',  c  c.  The  intermediate  skeleton,  with  numerous  branched  canals.  The  oblique 
lines  are  the  cleavage  planes  of  the  carbonate  of  lime,  extending  across  both  the  in- 
termediate skeleton  and  the  proper  wall.  (After  Carpenter.) 

also  penetrated  the  minute  tubes  of  the  proper  wall  and  the 
branching  canals  of  the  intermediate  skeleton.  In  some  cases 
the  chambers  are  simply  filled  with  crystalline  carbonate  of 
lime.  When  the  originally  porous  fossil  has  been  permeated 
by  a  silicate,  it  is  possible  to  dissolve  away  the  whole  of  the 
calcareous  skeleton  by  means  of  acids,  leaving  an  accurate  and 
beautiful  cast  of  the  chambers  and  the  tubes  connected  with 
them  in  the  insoluble  silicate. 

The  above  are  the  actual  appearances  presented  by  Eozoon 
when  examined  microscopically,  and  it  remains  to  see  how 
far  they  enable  us  to  decide  upon  its  true  position  in  the 
animal  kingdom.  Those  who  wish  to  study  this  interesting 
subject  in  detail  must  consult  the  admirable  memoirs  by  Dr. 
W.  B.  Carpenter  and  Principal  Dawson :  it  will  be  enough 
here  to  indicate  the  results  which  have  been  arrived  at.  The 
only  animals  at  the  present  day  which  possess  a  continuous 
calcareous  skeleton,  perforated  by  pores  and  penetrated  by 
canals,  are  certain  organisms  belonging  to  the  group  of  the 


72  HISTORICAL  PALEONTOLOGY. 

Foraminifera.  We  have  had  occasion  before  to  speak  of  these 
animals,  and  as  they  are  not  conspicuous  or  commonly-known 
forms  of  life,  it  may  be  well  to  say  a  few  words  as  to  the 
structure  of  the  living  representatives  of  the  group.  The 
Foraminifera  are  all  inhabitants  of  the  sea,  and  are  mostly  of 
small  or  even  microscopic  dimensions.  Their  bodies  are  com- 
posed of  an  apparently  structureless  animal  substance  of  an 
albuminous  nature  ("sarcode"),  of  a  gelatinous  consistence, 
transparent,  and  exhibiting  numerous  minute  granules  or 
rounded  particles.  The  body-substance  cannot  be  said  in 


Fig.  25.— The  animal  of  Nonionina,  one  of  the  Foraminifera,  after  the  shell  has  been 
removed  by  a  weak  acid;  6.  Gromia,  a  single-chambered  Foraminifer  (after  Schultze), 
showing  the  shell  surrounded  by  a  network  of  filaments  derived  from  the  body  substance. 

itself  to  possess  any  definite  form,  except  in  so  far  as  it  may 
be  bounded  by  a  shell;  but  it  has  the  power,  wherever  it  may 
be  exposed,  of  emitting  long  thread-like  filaments  ("pseudo- 
podia"),  which  interlace  with  one  another  to  form  a  network 
(fig.  25,  b).  These  filaments  can  be  thrown  out  at  will,  and 


THE  LAURENTTAN  AND  HURONIAN  PERIODS.     73 

to  considerable  distances,  and  can  be  again  retracted  into  the 
soft  mass  of  the  general  body-substance,  and  they  are  the 
agents  by  which  the  animal  obtains  its  food.  The  soft  bodies 
of  the  Foraminifera  are  protected  by  a  shell,  which  is  usually 


Tig.  26— Shells  of  living  Foraminifera.  a,  Orbulina  universa,  In  Its  perfect  condi- 
tion, showing  the  tubular  spines  which  radiate  from  the  surface  of  the  shell ;  ft,  Globi- 
gerina  bulloides,  In  its  ordinary  condition,  the  thin  hollow  spines  which  are  attached 
to  the  shell  when  perfect  having  been  broken  off ;  c,  Textularia  variabilte  ;  d,  Pener- 
oplis  planatus;  e,  Rotalia  concamerata;  /,  Cristellaria  subarcuatula.  [Fig.  a  is 
after  Wyville  Thomson;  the  others  are  after  Williamson.  All  the  figures  are  greatly 
enlarged.] 

calcareous,  but  may  be  composed  of  sand-grains  cemented 
together;  and  it  may  consist  of  a  single  chamber  (fig.  26,  a), 
or  of  many  chambers  arranged  in  different  ways  (fig.  26,  &-/). 
Sometimes  the  shell  has  but  one  large  opening  into  it — the 
mouth;  and  then  it  is  from  this  aperture  that  the  animal  pro- 
trudes the  delicate  net  of  filaments  with  which  it  seeks  its 
food.  In  other  cases  the  entire  shell  is  perforated  with 
minute  pores  (fig.  26,  e},  through  which  the  soft  body-substance 
gains  the  exterior,  covering  the  whole  shell  with  a  gelatinous 
film  of  animal  matter,  from  which  filaments  can  be  emitted  at 
any  point.  When  the  shell  consists  of  many  chambers,  all  of 


74  HISTORICAL  PALEONTOLOGY. 

these  are  placed  in  direct  communication  with  one  another, 
and  the  actual  substance  of  the  shell  is  often  traversed  by 
minute  canals  filled  with  living  matter  (e.g.,  in  Calcarina  and 
Nummulina).  The  shell,  therefore,  may  be  regarded,  in  such 
cases,  as  a  more  or  less  completely  porous  calcareous  structure, 
filled  to  its  minutest,  internal  recesses  with  the  substance  of 
the  living  animals,  and  covered  externally  with  a  layer  of  the 
same  substance,  giving  off  a  network  of  interlacing  filaments. 

Such,  in  brief,  is  the  structure  of  the  living  Foraminifera; 
and  it  is  believed  that  in  Eozo'on  we  have  an  extinct  example 
of  the  same  group,  not  only  of  special  interest  from  its  imme- 
morial antiquity,  but  hardly  less  striking  from  its  gigantic 
dimensions.  In  its  original  condition,  the  entire  chamber- 
system  of  Eozoon  is  believed  to  have  been  filled  with  soft 
structureless  living  matter,  which  passed  from  chamber  to 
chamber  through  the  wide  apertures  connecting  these  cavities, 
and  from  tier  to  tier  by  means  of  the  tubuli  in  the  shell-wall  and 
the  branching  canals  in  the  intermediate  skeleton.  Through 
the  perforated  shell-wall  covering  the  outer  surface  the  soft 
body-substance  flowed  out,  forming  a  gelatinous  investment, 
from  every  point  of  which  radiated  an  interlacing  net  of  deli- 
cate filaments,  providing  nourishment  for  the  entire  colony. 
In  its  present  state,  as  before  said,  all  the  cavities  originally 
occupied  by  the  body-substance  have  been  filled  with  some 
mineral  substance,  generally  with  one  of  the  silicates  of  mag- 
nesia; and  it  has  been  asserted  that  this  fact  militates  strongly 
against  the  organic  nature  of  Eozoon,  if  not  absolutely  dis- 
proving it.  As  a  matter  of  fact,  however — as  previously  no- 
ticed— it  is  by  no  means  very  uncommon  at  the  present  day 
to  find  the  shells  of  living  species  of  Foraminifera  in  which 
all  the  cavities  primitively  occupied  by  the  body-substance, 
down  to  the  minutest  pores  and  canals,  have  been  similarly 
injected  by  some  analogous  silicate,  such  as  glauconite. 

Those,  then,  whose  opinions  on  such  a  subject  deservedly 
carry  the  greatest  weight,  are  decisively  of  opinion  that  we  are 
presented  in  the  Eozoon  of  the  Laurentian  Rocks  of  Canada 
with  an  ancient,  colossal,  and  in  some  respects  abnormal  type 
of  the  Foraminifera.  In  the  words  of  Dr.  Carpenter,  it  is  not 
pretended  that  "  the  doctrine  of  the  Foraminiferal  nature  of 
Eosoon  can  be  proved  in  the  demonstrative  sense;"  but  it 
may  be  affirmed  "  that  the  convergence  of  a  number  of  separate 
and  independent  probabilities,  all  accordant  with  that  hypothesis, 
while  a  separate  explanation  must  be  invented  for  each  of 


THE  LAURENTIAN  AND  HURONIAN  PERIODS.     75 

them  on  any  other  hypothesis,  gives  it  that  high  probability 
on  which  we  rest  in  the  ordinary  affairs  of  life,  in  the  verdicts 
of  juries,  and  in  the  interpretation  of  geological  phenomena 
generally. " 

It  only  remains  to  be  added,  that  whilst  Eozo'on  is  by  far 
the  most  important  organic  body  hitherto  found  in  the  Lauren- 
tian,  and  has  been  here  treated  at  proportionate  length,  other 
traces  of  life  have  been  detected,  which  may  subsequently 
prove  of  great  interest  and  importance.  Thus,  Principal 
Dawson  has  recently  described  under  the  name  of  Archeeo- 
spharina  certain  singular  rounded  bodies  which  he  .  has  dis- 
covered in  the  Laurentian  limestones,  and  which  he  believes 
to  be  casts  of  the  shells  of  Foraminifera  possibly  somewhat 
allied  to  the  existing  Globigerina.  The  same  eminent  palaeon- 
tologist has  also  described  undoubted  worm-burrows  from 
rocks  probably  of  Laurentian  age.  Further  and  more  extended 
researches,  we  may  reasonably  hope,  will  probably  bring  to 
light  other  actual  remains  of  organisms  in  these  ancient  deposits. 
THE  HURONIAN  PERIOD. 

The  so-called  Huronian  Rocks,  like  the  Laurentian,  have 
their  typical  development  in  Canada,  and  derive  their  name 
from  the  fact  that  they  occupy  an  extensive  area  on  the  borders 
of  Lake  Huron.  They  are  wholly  metamorphic,  and  consist 
principally  of  altered  sandstones  or  quartzites,  siliceous,  fels- 
pathic,  or  talcose  slates,  conglomerates,  and  limestones.  They 
are  largely  developed  on  the  north  shore  of  Lake  Superior, 
and  give  rise  to  a  broken  and  hilly  country,  very  like  that 
occupied  by  the  Laurentians,  with  an  abundance  of  timber, 
but  rarely  with  sufficient  soil  of  good  quality  for  agricultural 
purposes.  They  are,  however,  largely  intersected  by  mineral 
veins,  containing  silver,  gold,  and  other  metals,  and  they  will 
ultimately  doubtless  yield  a  rich  harvest  to  the  miner.  The 
Huronian  Rocks  have  been  identified,  with  greater  or  less 
certainty,  in  other  parts  of  North  America,  and  also  in  the 
Old  World. 

The  total  thickness  of  the  Huronian  Rocks  in  Canada  is 
estimated  as  being  not  less  than  18,000  feet,  but  there  is  con- 
siderable doubt  as  to  their  precise  geological  position.  In  their 
typical  area  they  rest  unconformably  on  the  edge  of  strata  of 
Lower  Laurentian  age ;  but  they  have  never  been  seen  in  direct 
contact  with  the  Upper  Laurentian,  and  their  exact  relations 
to  this  series  are  therefore  doubtful.  It  is  thus  open  to  question 
whether  the  Huronian  Rocks  constitute  a  distinct  formation,  to 


76  HISTORICAL  PALEONTOLOGY. 

be  intercalated  in  point  of  time  between  the  Laurentian  and  the 
Cambrian  groups ;  or  whether,  rather,  they  should  not  be  con- 
sidered as  the  metamorphosed  representatives  of  the  Lower 
Cambrian  Rocks  of  other  regions. 

As  regards  the  fossils  of  the  Huronian  Rocks,  little  can  be 
said,  some  of  the  specimens  of  Eosoon  Canadense  which  have 
been  discovered  in  Canada  are  thought  to  come  from  rocks 
which  are  probably  of  Huronian  age.  In  Bavaria,  Dr.  Gumbel 
has  described  a  species  of  Eozoon  under  the  name  of  EozoVn 
Bavaricum,  from  certain  metamorphic  limestones  which  he 
refers  to  the  Huronian  formation.  Lastly,  the  late  Mr.  Billings 
described,  from  rocks  in  Newfoundland  apparently  referable  to 
the  Huronian,  certain  problematical  limpet-shaped  fossils,  to 
which  he  gave  the  name  of  Aspidclla. 
LITERATURE. 

Amongst  the  works  and  memoirs  which  the  student  may 
consult  with  regard  to  the  Laurentian  and  Huronian  deposits 
may  be  mentioned  the  following  :* — 

(1)  'Report  of  Progress  of  the  Geological  Survey  of  Canada 

from    its    Commencement   to    1863, '   pp.    38-49,    and   pp. 
50-66. 

(2)  '  Manual  of  Geology. '     Dana.  2nd  Ed.  1875. 

(3)  'The  Dawn  of  Life.'     J.  W.  Dawson.     1876. 

(4)  "  On  the  Occurrence  of  Organic  Remains  in  the  Lauren- 

tian  Rocks   of   Canada. "     Sir   W.   E.   Logan.     '  Quart. 
Journ.  Geol.  Soc., '  xxii.  45-50. 

(5)  "  On   the    Structure   of    Certain    Organic   Remains   in   the 

Laurentian    Limestones    of    Canada. "      J.    W.    Dawson. 
'Quart.    Journ.    Geol    Soc.,'   xxi.     51-59. 

(6)  "  Additional    Note    on    the    Structure    and    Affinities    of 

Eozoon  Canadense.  "     W.  B.  Carpenter.     '  Quart.  Journ. 
Geol.  Soc., '  xxi.  59-66. 

(7)  "  Supplemental   Notes  on  the   Structure   and  Affinities  of 

Eozoon  Canadense.  "      W.  B.  Carpenter.    '  Quart.  Journ. 
Geol.  Soc.,  xxi.  219-228. 

(8)  "  On  the  So-Called  Eozoonal  Rocks.  "     King  &  Rowney. 

'  Quart.  Journ.  Geol.  Soc., '  xxii.  185-218. 

(9)  '  Chemical  and  Geological  Essays. '     Sterry  Hunt. 

The  above  list  only  includes  some  of  the  more  important 
memoirs  which  may  be  consulted  as  to  the  geological  and  chem- 
ical features  of  the  Laurentian  and  Huronian  Rocks,  and  as 

*  In  this  and  in  all  subsequently  following  bibliographical  lists,  not 
only  is  the  selection  of  works  and  memoirs  quoted  necessarily  extremely 
limited ;  but  only  such  have,  as  a  general  rule,  been  chosen  for  mention  as 
are  easily  accessible  to  students  who  are  in  the  position  of  being  able  to 
refer  to  a  good  library.  Exceptions,  however,  are  occasionally  made  to 
this  rule,  in  favor  of  memoirs  or  works  of  special  historical  interest.  It 
is  also  unnecessary  to  add  that  it  has  not  been  thought  requisite  to  insert 
in  these  lists  the  well-known  handbooks  of  geological  and  palaeontological 
science,  except  in  such  instances  as  where  they  contain  special  information 
on  special  points. 


THE  LAURENTIAN  AND  HURON  IAN  PERIODS.     77 

to  the  true  nature  of  Eozoon.  Those  who  are  desirous  of  study- 
ing the  later  phases  of  the  controversy  with  regard  to  Eozo'on 
must  consult  the  papers  of  Carpenter,  Carter,  Dawson,  King  & 
Rowney,  Hahn,  and  others,  in  the  '  Quart.  Journ.  of  the  Geo- 
logical Society, '  the  '  Proceedings  of  the  Royal  Irsh  Academy, ' 
the  '  Annals  of  Natural  History, '  the  '  Geological  Magazine. '  &c. 
Dr.  Carpenter's  'Introduction  to  the  Study  of  the  Foraminifera ' 
should  also  be  consulted. 


CHAPTER  VIII. 
THE  CAMBRIAN  PERIOD. 

The  traces  of  life  in  the  Laurentian  period,  as  we  have  seen, 
are  but  scanty;  but  the  Cambrian  Rocks — so  called  from  their 
occurrence  in  North  Wales  and  its  borders  ("Cambria") — have 
yielded  numerous  remains  of  animals  and  some  dubious  plants. 
The  Cambrian  deposits  have  thus  a  special  interest  as  being 
the  oldest  rocks  in  which  occur  any  number  of  well-preserved 
and  unquestionable  organisms.  We  have  here  the  remains  of 
the  first  fauna,  or  assemblage  of  animals,  of  which  we  have  at 
present  knowledge.  As  regards  their  geographical  distribution, 
the  Cambrian  Rocks  have  been  recognized  in  many  parts  of 
the  world,  but  there  is  some  question  as  to  the  precise  limits 
of  the  formation,  and  we  may  consider  that  their  most  typical 
area  is  in* South  Wales,  where  they  have  been  carefully  worked 
out  chiefly  by  Dr.  Henry  Hicks.  In  this  region,  in  the  neigh- 
borhood of  the  promontory  of  St.  David's,  the  Cambrian  Rocks 
are  largely  developed,  resting  upon  an  ancient  ridge  of  Pre- 
Cambrian  (Laurentian?)  strata,  and  overlaid  by  the  lowest 
beds  of  the  Lower  Silurian.  The  subjoined  sketch-section 
(fig.  27)  exhibits  in  a  general  manner  the  succession  of  strata 
in  this  locality. 

From  this  section  it  will  be  seen  that  the  Cambrian 
Rocks  in  Wrales  are  divided  in  the  first  place  into  a  lower  and 
an  upper  group.  The  Lower  Cambrian  is  constituted  at  the 
base  by  a  great  series  of  grits,  sandstones,  conglomerates,  and 
slates,  which  are  known  as  the  "  Longmynd  group, "  from  their 
vast  development  in  the  Longmynd  Hills  in  Shropshire,  and 
which  attain  in  North  Wales  a  thickness  of  8000  feet  or  more. 
The  Longmynd  beds  are  succeeded  by  the  so-called  "  Mene- 
vian  group, "  a  series  of  sandstones,  flags,  and  grits,  about  600 
feet  in  thickness,  and  containing  a  considerable  number  of 
fossils.  The  Upper  Cambrian  series  consists  in  its  lower  por- 
tion of  nearly  5000  feet  of  strata,  principally  shaly  and  slaty, 


HISTORICAL  PALEONTOLOGY. 


which  are  known  as  the  "  Lingula  Flags, "  from  the  great 
abundance  in  them  of  a  shell  referable  to  the  genus  Lingula. 
These  are  followed  by  1000  feet  of  dark  shales  and  flaggy 
sandstones,  which  are  known  as  the  "  Tremadoc  slates, "  from 
their  occurrence  near  Tremadoc  in  North  Wales;  and  these 
in  turn  are  surmounted,  apparently  quite  conformably,  by  the 
basement  beds  of  the  Lower  Silurian. 

GENERALIZED  SECTION  OF  THE  CAMBRIAN  ROCKS  IN  WALES. 
Fig.  27. 

Arenig  Group    (Base  of 
the   Lower   Silurian). 

Tremadoc  Slates. 


Upper   Lingula  Flags. 
Middle  Lingula  Flags. 

Lower  Lingula  Flags. 
Menevian   Group. 


Longmynd     or     Harlech 
Group. 


Pre-Catnbrian  Rocks. 


THE  CAMBRIAN  PERIOD. 


79 


The  opposite  may  be  regarded  as  giving  a  typical  series  of 
the  Cambrian  Rocks  in  a  typical  locality;  but  strata  of  Cambrian 
age  are  known  in  many  other  regions,  of  which  it  is  only 
possible  here  to  allude  to  a  few  of  the  most  important.  In 
Scandinavia  occurs  a  well-developed  series  of  Cambrian  de- 
posits, representing  both  the  lower  and  upper  parts  of  the 
formation.  In  Bohemia,  the  Upper  Cambrian,  in  particular, 
is  largely  developed,  and  constitutes  the  so-called  "  Primordial 
zone  "  of  Barrande.  Lastly,  in  North  America,  whilst  the  Lower 
Cambrian  is  only  imperfectly  developed,  or  is  represented  by 
the  Huronian,  the  Upper  Cambrian  formation  has  a  wide  ex- 
tension, containing  fossils  similar  in  character  to  the  analogous 
strata  in  Europe,  and  known  as  the  "  Potsdam  Sandstone. " 
The  subjoined  table  shows  the  chief  areas  where  Cambrian 
Rocks  are  developed,  and  their  general  equivalency : 

TABULAR  VIEW  OF  THE  CAMBRIAN  FORMATION. 


Britain. 

Europe. 

America. 

a.  Tremadoc  Slates. 

a.  Primordial  zone 

a.  Potsdam 

of  Bohemia. 

Sandstone. 

Upper           H 

b.  I«ingula  Flags. 

b.  Paradoxides 

b.  Acadian 

Cambrian. 

Schists,     Olenus 
Schists,and  Dict- 

group  of  New 
Brunswick. 

yonema     schists 

of  Sweden. 

Huronian  For- 

a. I,ongmynd  Beds. 

a.  Fucoidal    Sand- 
stone of  Sweden. 

mation  ? 

b.  Uanberis  Slates. 

b.  Eophyton  Sand- 

stone of  Sweden. 

c.  Harlech  Grits. 

I,ower          4 

d.  Oldhamia  Slates  of 

Cambrian. 

Ireland. 

e.  Conglomerates  and 
Sandstones  of 

Sutherlandshire? 

f.  Menevian  Beds. 

Like  all  the  older  Palaeozoic  deposits,  the  Cambrian  Rocks, 
though  by  no  means  necessarily  what  would  be  called  actually 
"  metamorphic,  "  have  been  highly  cleaved,  and  otherwise  altered 
from  their  original  condition.  Owing  partly  to  their  indurated 
state,  and  partly  to  their  great  antiquity,  they  are  usually  found 
in  the  heart  of  mountainous  districts,  which  have  undergone 
great  disturbance,  and  have  been  subjected  to  an  enormous 
amount  of  denudation.  In  some  cases,  as  in  the  Longmynd 
Hills  in  Shropshire,  they  form  low  rounded  elevations,  largely 
covered  by  pasture,  and  with  few  or  no  elements  of  sublimity. 
In  other  cases,  however,  they  rise  into  bold  and  rugged 


80  HISTORICAL  PALEONTOLOGY. 

mountains,  girded  by  precipitous  cliffs.  Industrially,  the  Cam- 
brian Rocks  are  of  interest,  if  only  for  the  reason  that  the 
celebrated  Welsh  slates  of  Llanberis  are  derived  from  highly- 
cleaved  beds  of  this  age.  Taken  as  a  whole,  the  Cambrian 
formation  is  essentially  composed  of  arenaceous  and  muddy 
sediments,  the  latter  being  sometimes  red,  but  more  commonly 
nearly  black  in  color.  It  has  often  been  supposed  that  the  Cam- 
brians are  a  deep-sea  deposit,  and  that  we  may  thus  account 
for  the  few  fossils  contained  in  them ;  but  the  paucity  of  fossils 
is  to  a  large  extent  imaginary,  and  some  of  the  Lower  Cambrian 
beds  of  the  Longmynd  Hills  would  appear  to  have  been  laid 
down  in  shallow  water,  as  they  exhibit  rain-prints,  sun-cracks, 
and  ripple-marks — incontrovertible  evidence  of  their  having 
been  a  shore-deposit.  The  occurrence  of  innumerable  worm- 
tracks  and  burrows  in  many  Cambrian  strata  is  also  a  proof  of 
shallow-water  conditions ;  and  the  general  absence  of  limestones, 
coupled  with  the  coarse  mechanical  nature  of  many  of  the  sedi- 
ments of  the  Lower  Cambrian,  may  be  taken  as  pointing  in  the 
same  direction. 

The  life  of  the  Cambrian,  though  not  so  rich  as  in  the  suc- 
ceeding Silurian  period,  nevertheless  consists  of  representa- 
tives of  most  of  the  great  classes  of  invertebrate  animals.  The 
coarse  sandy  deposits  of  the  formation,  which  abound  more 
particularly  toward  its  lower  part,  naturally  are  to  a  large 
extent  barren  of  fossils;  but  the  muddy  sediments,  when  not 
too  highly  cleaved,  and  especially  towards  the  summit  of  the 
group,  are  replete  with  organic  remains.  This  is  also  the  case, 
in  many  localities  at  any  rate,  with  finer  beds  of  the  Potsdam 
Sandstone  in  America.  Limestones  are  known  to  occur  in 
only  a  few  areas  (chiefly  in  America),  and  this  may  account  for 
the  apparent  total  absence  of  corals.  It  is,  however,  interest- 
ing to  note  that,  with  this  exception,  almost  all  the  other  lead- 
ing groups  of  Invertebrates  are  known  to  have  come  into 
existence  during  the  Cambrian  period. 

Of  the  land-surfaces  of  the  Cambrian  period  we  know 
nothing;  and  there  is,  therefore,  nothing  surprising  in  the  fact 
that  our  acquaintance  with  the  Cambrian  vegetation  is  confined 
to  some  marine  plants  or  sea-weeds,  often  of  a  very  obscure  and 
problematical  nature.  The  "  Fucoidal  Sandstone "  of  Sweden, 
and  the  "  Potsdam  Sandstone "  of  North  America,  have  both 
yielded  numerous  remains  which  have  been  regarded  as  mark- 
ings left  by  sea-weeds  or  "  Fucoids ;  "  but  these  are  highly  enig- 
matical in  their  characters,  and  would,  in  many  instances,  seem 


THE  CAMBRIAN  PERIOD.  81 

to  be  rather  referable  to  the  tracks  and  burrows  of  marine 
worms.  The  first-mentioned  of  these  formations  has  also 
yielded  the  curious,  furrowed  and  striated  stems  which  have 
been  described  as  a  kind  of  land-plant  under  the  name  of 
Eophyton  (fig.  28).  It  cannot  be  said,  however,  that  the  vege- 


Fig.  28.— Fragment  of  Eophyton  Linneanum,  a  supposed  land-plant,  Lower 
Cambrian,  Sweden,  of  the  natural  size. 

table  origin  of  these  singular  bodies  has  been  satisfactorily 
proved.  Lastly,  there  are  found  in  certain  green  and  purple 
beds  of  Lower  Cambrian  age  at  Bray  Head,  Wicklow,  Ireland, 
some  very  remarkable  fossils,  which  are  well  known  under  the 
name  of  Oldhainia,  but  the  true  nature  of  which  is  very  doubtful. 
The  commonest  form  of  Oldhamia  (fig.  29)  consists  of  a 
thread-like  stem  or  axis,  from  which  spring  at  regular  intervals 
bundles  of  short  filamentous  branches  in  a  fan-like  manner. 
6 


82 


HISTORICAL  PALEONTOLOGY. 


In  the  locality  where  it  occurs,  the  fronds  of  Oldhamia  are  very 
abundant,  and  are  spread  over  the  surfaces  of  the  strata  in 
tangled  layers.  That  it  is  organic  is  certain,  and  that  it  is  a 
calcareous  sea-weed  is  probable;  but  it  may  possibly  belong  to 
the  sea-mosses  (Polyzoa),  or  to  the  sea-firs  (Sertularians). 

Amongst  the  lower  forms  of  animal  life  (Protozoa^,  we  find 
the  Sponges  represented  by  the  curious  bodies,  composed  of 
netted  fibres,  to  which  the  name  of  Protospongia  has  been  given 
(fig.  32,  a)  ;  and  the  comparatively  gigantic,  conical,  or  cylin- 
drical fossils  termed  Archceocyathus  by  Mr.  Billings  are  certainly 
referable  either  to  the  Foraminifera  or  to  the  Sponges.  The 
almost  total  absence  of  lime- 
stones in  the  formation  may 
be  regarded  as  a  sufficient  ex- 
planation of  the  fact  that  the 
Foraminifera  are  not  more 
largely  and  unequivocally  rep- 
resented; though  the  exist- 
ence of  greensands  in  the 
Cambrian  beds  of  Wisconsin 
and  Tennessee  may  be  taken 
as  an  indication  that  this  class 
of  animals  was  by  no  means 
wholly  wanting.  The  same 
fact  may  explain  the  total  ab- 
sence of  corals,  so  far  as  at 
present  known. 

The  group  of  the  Eichi- 
nodermaia  (Sea-lilies,  Sea- 
urchins,  and  their  allies)  is 
represented  by  a  few  forms, 

which  are  principally  of  interest  as  being  the  earliest-known 
examples  of  the  class.  It  is  also  worthy  of  note  that  these 
precursors  of  a  group  which  subsequently  attains  such  geo- 
logical importance,  are  referable  to  no  less  than  three  distinct 
orders — the  Crinoids  or  Sea-lilies,  represented  by  a  species  of 
Deiidrocrinus;  the  Cystideans  by  Protocystites;  and  the  Star- 
fishes by  Palasterina  and  some  other  forms.  Only  the  last 
of  these  groups,  however,  appears  to  occur  in  the  Lower 
Cambrian. 

The  Ringed-worms  (Annelida},  if  rightly  credited  with  all 
the  remains  usually  referred  to  them,  appear  to  have  swarmed 
in  the  Cambrian  seas.  Being  soft-bodied,  we  do  not  find  the 


Fig.  29.— A  portion  of  Oldhamia  an- 
tiqua,  Lower  Cambrian,  Wicklow,  Ire- 
land, of  the  natural  size.  (AfterSalter.) 


THE  CAMBRIAN  PERIOD.  83 

actual  worms  themselves  in  the  fossil  condition,  but  we  have, 
nevertheless,  abundant  traces  of  their  existence.  In  some 
cases  we  find  vertical  burrows  of  greater  or  less  depth,  often 
expanded  towards  their  apertures,  in  which  the  worm  must 
have  actually  lived  (fig.  30),  as  various  species  do  at  the  pres- 


Fig.  30.— Annelide-burrows  (Scolitfiua  linearis),  from  the  Potsdam  Sandstone 
of  Canada,  of  the  natural  size.    (After  Billings.) 


ent  day.  In  these  cases,  the  tube  must  have  been  rendered 
more  or  less  permanent  by  receiving  a  coating  of  mucus,  or 
perhaps  a  genuine  membraneous  secretion,  from  the  body  of 
the  animal,  and  it  may  be  found  quite  empty,  or  occupied  by 
a  cast  of  sand  or  mud.  Of  this  nature  are  the  burrows  which 
have  been  described  under  the  names  of  Scolithus  and  Scoleco- 
derma,  and  probably  the  Histioderma  of  the  Lower  Cambrian 
of  Ireland.  In  other  cases,  as  in  Arenicolites  (fig.  32,  &),  the 
worm  seems  to  have  inhabited  a  double  burrow,  shaped  like 
the  letter  U,  and  having  two  openings  placed  close  together 
on  the  surface  of  the  stratum.  Thousands  of  these  twin- 
burrows  occur  in  some  of  the  strata  of  the  Longmynd,  and  it 
is  supposed  that  the  worm  used  one  opening  to  the  burrow  as 
an  aperture  of  entrance,  and  the  other  as  one  of  exit.  In  other 
cases,  again,  we  find  simply  the  meandering  trails  caused  by 
the  worm  dragging  its  body  over  the  surface  of  the  mud. 
Markings  of  this  kind  are  commoner  in  the  Silurian  Rocks, 
and  it  is  generally  more  or  less  doubtful  whether  they  may 
not  have  been  caused  by  other  marine  animals,  such  as  shell- 


84  HISTORICAL  PALAEONTOLOGY. 

fish,  whilst  some  of  them  have  certainly  nothing  whatever  to 
do  with  the  worms.  Lastly,  the  Cambrian  beds  often  show 
twining  cylindrical  bodies,  commonly  more  or  less  matted 
together,  and  not  confined  to  the  surfaces  of  the  strata,  but 
passing  through  them.  These  have  often  been  regarded  as 
the  remains  of  sea-weeds,  but  it  is  more  probable  that  they 
represent  casts  of  the  underground  burrows  of  worms  of  simi- 
lar habits  to  the  common  lob-worm  (Arenicola)  of  the  present 
day. 

The  Articulate  animals  are  numerously  represented  in  the 
Cambrian  deposits,  but  exclusively  by  the  class  of  Crustaceans. 
Some  of  these  are  little  double-shelled  creatures,  resembling 
our  living  water-fleas  (Ostracoda).  A  few  are  larger  forms,  and 
belong  to  the  same  group  as  the  existing  brine-shrimps  and 
fairy-shrimps  (Phyllopoda).  One  of  the  most  characteristic  of 
these  is  the  Hyvnenocaris  vermicauda  of  the  Lingula  Flags  (fig. 
32,  d).  By  far  the  larger  number  of  the  Cambrian  Crustacea 
belong,  however,  to  the  remarkable  and  wholly  extinct  group 
of  the  Trilobites.  These  extraordinary  animals  must  have 
literally  swarmed  in  the  seas  of  the  later  portion  of  this  and 
the  whole  of  the  succeeding  period;  and  they  survived  in 
greatly  diminished  numbers  till  the  earlier  portion  of  the 
Carboniferous  period.  They  died  out,  however,  wholly  before 
the  close  of  the  Palaeozoic  epoch,  and  we  have  no  Crusta- 
ceans at  the  present  day  which  can  be  considered  as  their 
direct  representatives.  They  have,  however,  relationships  of 
a  more  or  less  intimate  character  with  the  existing  groups  of 
the  Phyllopods,  the  King-crabs  (Limulus},  and  the  Isopods 
("Slaters,"  Wood-lice,  &c.)  Indeed,  one  member  of  the  last- 
mentioned  order,  namely,  the  Serolis  of  the  coasts  of  Patagonia, 
has  been  regarded  as  the  nearest  living  ally  of  the  Trilobites. 
Be  this  as  it  may,  the  Trilobites  possessed  a,  skeleton  which, 
though  capable  of  undergoing  almost  endless  variations,  was 
wonderfully  constant  in  its  pattern  of  structure,  and  we  may 
briefly  describe  here  the  chief  features  of  this. 

The  upper  surfaces  of  the  body  of  a  Trilobite  was  defended 
by  a  strong  shell  or  "  crust, "  partly  horny  and  partly  calcare- 
ous in  its  composition.  This  shell  (fig.  31)  generally  exhibits 
a  very  distinct  "  trilobation  "  or  division  into  three  longitudinal 
lobes,  one  central  and  two  lateral.  It  also  exhibits  a  more 
important  and  more  fundamental  division  into  three  transverse 
portions,  which  are  so  loosely  connected  with  one  another  as 
very  commonly  to  be  found  separate.  The  first  and  most 


THE  CAMBRIAN  PERIOD. 


anterior  of  these  divisions  is  a  shield  or  buckler  which  covers 
the  head;  the  second  or  middle  portion  is  composed  of  mov- 
able rings  covering  the  trunk  ("thorax");  and  the  third  is  a 
shield  which  covers  the  tail  or  "  abdomen. "  The  head-shield 
(fig.  31,  e)  is  generally  more  or  less  semicircular  in  shape;  and 
its  central  portion,  covering  the  stomach  of  the  animal,  is  usu- 
ally strongly  elevated,  and  generally  marked  by  lateral  furrows. 
A  little  on  each  side  of  the  head  are  placed  the  eyes,  which 
are  generally  crescentic  in  shape,  and  resemble  the  eyes  of 
insects  and  many  existing  Crustaceans  in  being  "  compound, " 
or  made  up  of  numerous  simple  eyes  aggregated  together. 
So  excellent  is  the  state  of  preservation  of  many  specimens  of 
Trilobites,  that  the  numerou0  individual  lenses  of  the  eyes 
have  been  uninjured,  and  as  many  as  four  hundred  have  been 
counted  in  each  eye  of  some  forms.  The  eyes  may  be  sup- 
ported upon  prominences,  but  they  are  never  carried  on  mov- 


Fig.  31.— Cambrian  Trilobites:  a,  Paradoxidea  Bohemicua,  reduced  In  size;  6,  Elllp- 
socephalus  Hoffl;  c,  Sao  fiirsuta;  d,  Conocorypfie  Sultzeri  (all  the  above,  together  with 
fig.  g,  are  from  the  Upper  Cambrian  or  "Primordial  Zone"  of  Bohemia);  e.  Head-shield 
of  Dikelloccphalua  Celticus,  from  the  Llngula  Flags  of  Wales;/,  Head-shield  of  Cono- 
coryphe  Matthewi,  from  the  Upper  Cambrian  (Acadian  Group)  of  New  Brunswick;  g, 
Affnostus  rex,  Bohemia;  h,  Tail-shield  of  Dikellocephalus  M Innesotensis ,  from  the 
Upper  Cambrian  (Potsdam  Sandstone)  of  Minnesota.  (After  Barrande,  Dawson,  Salter, 
and  Dale  Owen.) 


86  HISTORICAL  PALEONTOLOGY. 

able  stalks  (as  they  are  in  the  existing  lobsters  and  crabs)  ;  and 
in  some  of  the  Cambrian  Trilobites,  such  as  the  little  Agnosti 
(fig.  31,  g),  the  animal  was  blind.  The  lateral  portion  of  the 
head-shield  are  usually  separated  from  the  central  portion  by 
a  peculiar  line  of  division  (the  so-called  "  facial  suture ")  on 
each  side ;  but  this  is  also  wanting  in  some  of  the  Cambrian 
species.  The  backward  angles  of  the  head-shield,  also,  are 
often  prolonged  into  spines,  which  sometimes  reach  a  great 
length.  Following  the  head-shield  behind,  we  have  a  portion 
of  the  body  which  is  composed  of  movable  segments  or  "body- 
rings,  "  and  which  is  technically  called  the  "  thorax. "  Ordi- 
narily, this  region  is  strongly  trilobed,  and  each  ring  consists  of 
a  central  convex  portion,  and  of  two  flatter  side-lobes.  The 
number  of  body-rings  in  the  thorax  is  very  variable  (from  two 
to  twenty-six),  but  is  fixed  for  the  adult  forms  of  each  group  of 
the  Trilobites.  The  young  forms  have  much  fewer  rings  than 
the  rull-grown  ones;  and  it  is  curious  to  find  that  the  Cam- 
brian Trilobites  very  commonly  have  either  a  great  many  rings 
(as  in  Paradoxides,  fig.  31,  a),  or  else  very  few  (as  in  Agnostus, 
fig-  31*  d)-  In  some  instances,  the  body-rings  do  not  seem  to 
have  been  so  constructed  as  to  allow  of  much  movement,  but 
in  other  cases  this  region  of  the  body  is  so  flexible  that  the 
animal  possessed  th^  power  of  rolling  itself  up  completely,  like 
a  hedgehog;  and  many  individuals  have  been  permanently 
preserved  as  fossils  in  this  defensive  condition.  Finally,  the 
body  of  the  Trilobite  was  completed  by  a  tail-shield  (technic- 
ally termed  the  "pygidium"),  which  varies  much  in  size  and 
form,  and  is  composed  of  a  greater  or  less  number  of  rings, 
similar  to  those  which  form  the  thorax,  but  immovably  amalga- 
mated with  one  another  (fig.  31,  7i). 

The  under  surface  of  the  body  in  the  Trilobites  appears  to 
have  been  more  or  less  entirely  destitute  of  hard  structures, 
with  the  exception  of  a  well-developed  upper  lip,  in  the  form 
of  a  plate  attached  to  the  inferior  side  of  the  head-shield  in 
front.  There  is  no  reason  to  doubt  that  the  animal  possessed 
legs;  but  these  structures  seem  to  have  resembled  those  of 
many  living  Crustaceans  in  being  quite  soft  and  membranous. 
This,  at  any  rate,  seems  to  have  been  generally  the  case ; 
though  structures  which  have  been  regarded  as  legs  have  been 
detected  on  the  under  surface  of  one  of  the  larger  species  of 
Trilobites.  There  is  also,  at  present,  no  direct  evidence  that 
the  Trilobites  possessed  two  pairs  of  jointed  feelers  ("an- 
tennae") which  are  so  characteristic  of  recent  Crustaceans. 


THE  CAMBRIAN  PERIOD.  87 

The  Trilobites  vary  much  in  size,  and  the  Cambrian  forma- 
tion presents  examples  of  both  the  largest  and  the  smallest 
members  of  the  order.  Some  of  the  young  forms  may  be  little 
bigger  than  a  millet-seed,  and  some  adult  examples  of  the 
smaller  species  (such  as  Agnostus)  may  be  only  a  few  lines  in 
length;  whilst  such  giants  of  the  order  as  Paradoxides  and 
Asaphus  may  reach  a  length  of  from  one  to  two  feet.  Judging 
from  what  we  actually  know  as  to  the  structure  of  the  Trilo- 
bites, and  also  from  analogous  recent  forms,  it  would  seem  that 
these  ancient  Crustaceans  were  mud-haunting  creatures,  deni- 
zens of  shallow  seas,  and  affecting  the  soft  silt  of  the  bottom 
rather  than  the  clear  water  above.  Whenever  muddy  sedi- 
ments are  found  in  the  Cambrian  and  Silurian  formations, 
there  we  are  tolerably  sure  to  find  Trilobites,  though  they  are 
by  no  means  absolutely  wanting  in  limestones.  They  appear 
to  have  crawled  about  upon  the  sea-bottom,  or  burrowed  in  the 
yielding  mud,  with  the  soft  under  surface  directed  downwards ; 
and  it  is  probable  that  they  really  derived  their  nutriment  from 
the  organic  matter  contained  in  the  ooze  amongst  which  they 
lived.  The  vital  organs  seem  to  have  occupied  the  central  lobe 
of  the  skeleton,  by  which  they  were  protected;  and  a  series  of 
delicate  leaf-like  paddles,  which  probably  served  as  respiratory 
organs,  would  appear  to  have  been  carried  on  the  under  surface 
of  the  thorax.  That  they  had  their  enemies  may  be  regarded 
as  certain;  but  we  have  no  evidence  that  they  were  furnished 
with  any  offensive  weapons,  or,  indeed,  with  any  means  of 
defence  beyond  their  hard  crust,  and  the  power,  possessed  by 
so  many  of  them,  of  rolling  themselves  into  a  ball.  An  addi- 
tional proof  of  the  fact  that  they  for  the  most  part  crawled 
along  the  sea-bottom  is  found  in  the  occurrence  of  tracks  and 
markings  of  various  kinds,  which  can  hardly  be  ascribed  to 
any  other  creatures  with  any  show  of  probability.  That  this, 
is  the  true  nature  of  some  of  the  markings  in  question  cannot 
be  doubted  at  all ;  and  in  other  cases  no  explanation  so  prob- 
able has  yet  suggested.  If,  however,  the  tracks  which 
have  been  described  from  the  Potsdam  Sandstone  of  North 
America  under  the  name  of  Protichnites  are  really  due  to  the 
peregrinations  of  some  Trilobite,  they  must  have  been  pro- 
duced by  one  of  the  largest  examples  of  the  order. 

As  already  said,  the  Cambrian  Rocks  are  very  rich  in  the 
remains  of  Trilobites.  In  the  lowest  beds  of  the  series  (Long- 
mynd  Rocks),  representatives  of  some  half-dozen  genera  have 
now  been  detected,  including  the  dwarf  Agnostus  and  the  giant 


88 


HISTORICAL  PALAEONTOLOGY. 


Paradoxides.  In  the  higher  beds,  the  number  both  of  genera 
and  species  is  largely  increased ;  and  from  the  great  compara- 
tive abundance  of  individuals,  the  Trilobites  have  every  right 
to  be  considered  as  the  most  characteristic  fossils  of  the  Cam- 
brian period, — the  more  so  as  the  Cambrian  species  belong  to 
peculiar  types,  which,  for  the  most  part,  died  out  before  the 
commencement  of  the  Silurian  epoch. 

All  the  remaining  Cambrian  fossils  which  demand  any  notice 
here  are  members  of  one  or  other  division  of  the  great  class 
of  the  Mollusca,  or  "  Shell-fish "  properly  so  called.  In  the 
Lower  Cambrian  Rocks  the  Lamp-shells  (Brachiopoda}  are  the 
principal  or  sole  representatives  of  the  class,  and  appear  chiefly 
in  three  interesting  and  important  types— namely,  Lingulella, 


Fig.  32.— Cambrian  Fossils:  a,  Protospongia  fenestrata,  Menevian  Group;  b,  Areni- 
colites  didymus,  Longmynd  Group ;  c,  Lingulella  ferruginea,  Longmynd  and  Mene- 
vian, enlarged;  d,  Hymenocaris  vermicauda,  Lingula  Flags;  e.  Lingulella  Davisii, 
Lingula  Flags;  /,  Orthis  lenticularis,  Lingula  Flags;  g,  Theca  Davidii,  Tremadoc 
Slates;  h,  Modiolopsis  Solvensis,TTein&&oc  Slates;  i,  Obolclla  sagittalis,  interior  of  valve, 
Menevian ;.?,  Exterior  of  the  same;  k,  Orthis  Hicksii,  Menevian;  I,  Cast  of  the  same; 
m,  Olenut  micrurus,  Lingula  Flags.  (After  Salter,  Hicks  and  Davidson.) 

Discina,  and  Obolella.  Of  these  the  last  (fig.  32,  «)  is  highly 
characteristic  of  these  ancient  deposits ;  whilst  Discina  is  one 
of  those  remarkable  persistent  types  which,  commencing  at 
this  early  period,  has  continued  to  be  represented  by  varying 
forms  through  all  the  intervening  geological  formations  up  to 
the  present  day.  Lingulella  (fig.  32,  c),  again,  is  closely  allied 


THE  CAMBRIAN  PERIOD. 


to  the  existing  "Goose-bill"  Lamp-shell  (Lingula  anatina),  and 
thus  presents  us  with  another  example  of  an  extremely  long- 
lived  type.  The  Lingulellce  and  their  successors,  the  Lingula, 
are  singular  in  possessing  a  shell  which  is  of  a  horny  texture, 
and  contains  but  a  small  proportion  of  calcareous  matter.  In 
the  Upper  Cambrian  Rocks,  the  Lingulella  become  much  more 
abundant,  the  broad  satchel-shaped  species  known  as  L.  Davisii 
(fig.  32,  e)  being  so  abundant  that  one  of  the  great  divisions  of 
the  Cambrian  is  termed  the  "  Lingula  Flags. "  Here,  also,  we 
meet  for  the  first  time  with  examples  of  the  genus  Orthis  (fig.  32,  /, 
k,  /)  a  characteristic  Palaeozoic  type  of  the  Brachiopods,  which  is 
destined  to  undergo  a  vast  extension  in  later  ages. 

Of  the  higher  groups  of  the  Mollusca  the  record  is  as  yet 
but  scanty.  In  the  Lower  Cambrian,  we  have  but  the  thin, 
fragile,  dagger-shaped  shells  of  the  free-s\vimming  oceanic 
Molluscs  or  "Winged-snails"  (Pteropoda),  of  which  the  most 
characteristic  is  the  genus  Theca  (fig.  32,  g).  In  the  upper 
Cambrian,  in  addition  to  these,  we  have  a  few  Univalves 
(Gasteropoda),  and,  thanks  to  the  researches  of  Dr.  Hicks, 
quite  a  small  assemblage  of  Bivalves  (Lamellibranchiata), 
though  these  are  mostly  of  no  great  dimensions  (fig.  32,  h). 
Of  the  chambered  Cephalopoda  (Cuttle-fishes  and  their  allies), 
we  have  but  few  traces,  and  these  wholly  confined  to  the  higher 
beds  of  the  formation.  We  meet,  however,  with  examples  of 
the  wonderful  genus  Orthoceras,  with  its 
straight,  partitioned  shell,  which  we  shall 
find  in  an  immense  variety  of  forms  in  the 
Silurian  rocks.  Lastly,  it  is  worthy  of 
note  that  the  lowest  of  all  the  groups  of 
the  Mollusca — namely,  that  of  the  Sea- 
mats,  Sea-mosses,  and  Lace-corals  (Poly- 
zoa) — is  only  doubtfully  known  to  have 
any  representatives  in  the  Cambrian, 
though  undergoing  a  large  and  varied 
development  in  the  Silurian  deposits. 

An  exception,  however,  may  with 
much  probability  be  made  to  this  state- 
ment in  favor  of  the  singular  genus 
Dictyoncma  (fig.  33),  which  is  highly 
characteristic  of  the  highest  Cambrian  beds 
(Tremadoc  Slates).  This  curious  fossil 
occurs  in  the  form  of  fan-like  or  funnel- 
shaped  expansions,  composed  of  slightly-diverging  horny 


Fig.  33.— Fragment  of 
Dictyonema  sociale,  con- 
siderably enlarged,  show- 
Ing  the  horny  branches, 
with  their  connecting 
cross-bars,  and  with  a  row 
of  cells  on  each  side. 
(Original.) 


90  HISTORICAL  PALEONTOLOGY. 

branches,  which  are  united  in  a  net-like  manner  by  numerous 
delicate  cross-bars,  and  exhibit  a  row  of  little  cups  or  cells,  in 
which  the  animals  were  contained,  on  each  side.  Dictyonema 
has  generally  been  referred  to  the  Graptolites;  but  it  has  a  much 
greater  affinity  with  the  plant-like  Sea-firs  (Sertularians)  or  the 
Sea-mosses  (Polysoa),  and  the  balance  of  evidence  is  perhaps 
in  favor  of  placing  it  with  the  latter. 

LITERATURE. 

The  following  are  the  more  important  and  accessible  works 
and  memoirs  which  may  be  consulted  in  studying  the  strati- 
graphical  and  palaeontological  relations  of  the  Cambrian 
Rocks  :— 

(1)  'Siluria. '     Sir  Roderick  Murchison.     5th  ed.,  pp.  21-46. 

(2)  'Synopsis  of  the   Classification  of  the  British   Palaeozoic 

Rocks. '  Sedgwick.  Introduction  to  the  3d  Fasciculus 
of  the  '  Descriptions  of  British  Palaeozoic  Fossils  in  the 
Woodwardian  Museum, '  By  F.  M'Coy,  pp.  i-xcviii, 
1855. 

(3)  '  Catalogue  of  the  Cambrian  and  Silurian  Fossils  in  the 

Geological  Museum  of  the  University  of  Cambridge. ' 
Salter.  With  a  Preface  by  Prof.  Sedgwick.  1873. 

(4)  'Thesaurus  Siluricus. '     Bigsby.     1868. 

(5)  "  History  of  the  Names  Cambrian  and  Silurian. "  Sterry 

Hunt. — '  Geological  Magazine. '     1873. 

(6)  '  Systeme  Silurien  du  Centre  de  la  Boheme. '     Barrande. 

Vol.  I. 

(7)  '  Report  of  Progress  of  the  Geological  Survey  of  Canada, 

from  its  Commencement  to  1863, '  pp.  87-109. 

(8)  'Acadian  Geology.'     Dawson.     Pp.  641-657. 

(9)  "  Guide  to  the  Geology  of  New  York, "     Lincklaen ;  and 

"  Contributions  to  the  Palaeontology  of  New  York, " 
James  Hall. — '  Fourteenth  Report  on  the  State  Cabinet. ' 
1861. 

(10)  'Palaeozoic  Fossils  of  Canada.'    Billings.     1865. 

(n)  'Manual    of    Geology.'      Dana.      Pp.    166-182.      2nd    ed. 
1875- 

(12)  "Geology  of  North  Wales,"  Ramsay;  with  Appendix  on 

the  Fossils,  Salter. — '  Memoirs  of  the  Geological  Sur- 
vey of  Great  Britain, '  vol.  iii,  1866. 

(13)  "  On  the  Ancient  Rocks  of  the  St.  David's  Promontory, 

South  Wales,  and  their  Fossil  Contents. "  Harkness 
and  Hicks. — '  Quart.  Journ.  Geol.  Soc., '  xxvii.  384- 
402.  1871. 


THE  CAMBRIAN  PERIOD.  91 

(14)  "On  the  Tremadoc  Rocks  in  the  Neighborhood  of  St. 
David's,  South  Wales,  and  their  Fossil  Contents. " 
Hicks. — '  Quart  Journ.  Geol.  Soc., '  xxix.  39-52  1873. 

In  the  above  list,  allusion  has  necessarily  been  omitted  to  num- 
erous works  and  memoirs  on  the  Cambrian  deposits  of  Sweden 
and  Norway,  Central  Europe,  Russia,  Spain,  and  various  parts 
of  North  America,  as  well  as  to  a  number  of  important  papers 
on  the  British  Cambrian  strata  by  various  well-known  observers. 
Among  these  latter  may  be  mentioned  memoirs  by  Prof.  Phillips, 
and  Messrs  Salter,  Hicks,  Belt,  Plant,  Homfray,  Ash,  Holl,  &c. 


CHAPTER  IX. 

THE  LOWER  SILURIAN  PERIOD. 

The  great  system  of  deposits  to  which  Sir  Roderick  Murchi- 
son  applied  the  name  of  "  Silurian  Rocks "  reposes  directly 
upon  the  highest  Cambrian  beds,  apparently  without  any 
marked  unconformity,  though  with  a  considerable  change  in 
the  nature  of  the  fossils.  The  name  "  Silurian  "  was  originally 
proposed  by  the  eminent  geologist  just  alluded  to  for  a  great 
series  of  strata  lying  below  the  Old  Red  Sandstone,  and  occu- 
pying districts  in  Wales  and  its  borders  which  were  at  one 
time  inhabited  by  the  "  Silures, "  a  tribe  of  ancient  Britons. 
Deposits  of  a  corresponding  age  are  now  known  to  be  largely 
developed  in  other  parts  of  England,  in  Scotland,  and  in  Ire- 
land, in  North  America,  in  Australia,  in  India,  in  Bohemia, 
Saxony,  Bavaria,  Russia,  Sweden  and  Norway,  Spain,  and  in 
various  other  regions  of  less  note.  In  some  regions,  as  in  the 
neighborhood  of  St.  Petersburg,  the  Silurian  strata  are  found 
not  only  to  have  preserved  their  original  horizontality,  but  also 
to  have  retained  almost  unaltered  their  primitive  soft  and  inco- 
herent nature.  In  other  regions,  as  in  Scandinavia  and  many 
parts  of  North  America,  similar  strata,  now  consolidated  into 
shales,  sandstones,  and  limestones,  may  be  found  resting  with 
a  very  slight  inclination  on  still  older  sediment.  In  a  great 
many  regions,  however,  the  Silurian  deposits  are  found  to  have 
undergone  more  or  less  folding,  crumpling,  and  dislocation, 
accompanied  by  induration  and  "  cleavage "  of  the  finer  and 


92  HISTORICAL  PALAEONTOLOGY. 

softer  sediments ;  whilst  in  some  regions,  as  in  the  Highlands 
of  Scotland,  actual  "  metamorphism "  has  taken  place.  In 
consequence  of  the  above,  Silurian  districts  usually  present 
the  bold,  rugged,  and  picturesque  outlines  which  are  char- 
acteristic of  the  older  "  Primitive  "  rocks  of  the  earth's  crust  in 
general.  In  many  instances,  we  find  Silurian  strata  rising  into 
mountain-chains  of  great  grandeur  and  sublimity,  exhibiting 
the  utmost  diversity  of  which  rock-scenery  is  capable,  and  de- 
lighting the  artist  with  endless  changes  of  valley,  lake,  and 
cliff.  Such  districts  are  little  suitable  for  agriculture,  though 
this  is  often  compensated  for  by  the  valuable  mineral  products 
contained  in  the  rocks.  On  the  other  hand,  when  the  rocks  are 
tolerably  soft  and  uniform  in  their  nature,  or  when  few  disturb- 
ances of  the  crust  of  the  earth  have  taken  place,  we  may  find 
Silurian  areas  to  be  covered  with  an  abundant  pasturage  or  to 
be  heavily  timbered. 

Under  the  head  of  "  Silurian  Rocks, "  Sir  Roderick  Murchi- 
son  included  all  the  strata  between  the  summit  of  the  "  Long- 
mynd  "  beds  and  the  Old  Red  Sandstone,  and  he  divided  these 
into  the  two  great  groups  of  the  Lower  Silurian  and  Upper  Silu- 
rian. It  is,  however,  now  generally  admitted  that  a  considerable 
portion  of  the  basement  beds  of  Murchison's  Silurian  series 
must  be  transferred — if  only  upon  palseontological  grounds — to 
the  Upper  Cambrian,  as  has  here  been  done;  and  much  contro- 
versy has  been  carried  on  as  to  the  proper  nomenclature  of  the 
Upper  Silurian  and  of  the  remaining  portion  of  Murchison's 
Lower  Silurian.  Thus,  some  would  confine  the  name  "  Silu- 
rian "  exclusively  to  the  Upper  Silurian,  and  would  apply  the 
name  of  "  Cambro-Silurian "  to  the  Lower  Silurian,  or  would 
include  all  beds  of  the  latter  age  in  the  "  Cambrian "  series  of 
Sedgwick.  It  is  not  necessary  to  enter  into  the  merits  of  these 
conflicting  views.  For  our  present  purpose,  it  is  sufficient  to 
recognize  that  there  exist  two  great  groups  of  rocks  between 
the  highest  Cambrian  beds,  as  here  defined,  and  the  base  of 
the  Devonian  or  Old  Red  Sandstone.  These  two  great  groups 
are  so  closely  allied  to  one  another,  both  physically  and  palae- 
ontologically,  that  many  authorities  have  established  a  third 
or  intermediate  group  (the  "Middle  Silurian"),  by  which  a  pas- 
sage is  made  from  one  into  the  other.  This  method  of  pro- 
cedure involves  disadvantages  which  appear  to  outweigh  its 
advantages;  and  the  two  groups  in  question  are  not  only  gen- 
erally capable  of  very  distinct  stratigraphical  separation,  but  at 
the  same  time  exhibit,  together  with  the  alliances  above  spoken 


THE  LOWER  SILURIAN  PERIOD.  93 

of,  so  many  and  such  important  palaeontological  differences, 
that  it  is  best  to  consider  them  separately.  We  shall  there- 
fore follow  this  course  in  the  present  instance;  and  pending 
the  final  solution  of  the  controversy  as  to  Cambrian  and  Silu- 
rian nomenclature,  we  shall  distinguish  these  two  groups  of 
strata  as  the  "  Lower  Silurian  "  and  the  "  Upper  Silurian. " 

The  Lower  Silurian  Rocks  are  known  already  to  be  devel- 
oped in  various  regions;  and  though  their  general  succession 
in  these  areas  is  approximately  the  same,  each  area  exhibits 
peculiarities  of  its  own,  whilst  the  subdivisions  of  each  are 
known  by  special  names.  All,  therefore,  that  can  be  attempted 
here,  is  to  select  two  typical  areas — such  as  Wales  and  North 
America — and  to  briefly  consider  the  grouping  and  divisions 
of  the  Lower  Silurian  in  each. 

In  Wales,  the  line  between  the  Cambrian  and  Lower  Silurian 
is  somewhat  ill-defined,  and  is  certainly  not  marked  by  any 
strong  unconformity.  There  are,  however,  grounds  for  accept- 
ing the  line  proposed,  for  paLneontological  reasons,  by  Dr. 
Hicks,  in  accordance  with  which  the  Tremadoc  Slates  ("Lower 
Tremadoc "  of  Salter)  become  the  highest  of  the  Cambrian 
deposits  of  Britain.  If  we  take  this  view,  the  Lower  Silurian 
rocks  of  Wales  and  adjoining  districts  are  found  to  have  the 
following  general  succession  from  below  upwards  (fig.  34)  : — 

1.  The  Arenig   Group. — This  group   derives   its  name   from 
the   Arenig   mountains,    where   it   is   extensively   developed.      It 
consists  of  about  4000  feet  of  slates,  shales,  and  flags,  and  is 
divisible  into  a  lower,  middle,  and  upper  division,  of  which  the 
former    is    often    regarded    as    Cambrian    under    the    name    of 
"  Upper  Tremadoc  Slates.  " 

2.  The  Llandeilo  Group. — The  thickness  of  this  group  varies 
from  about  4000  to  as  much  as  10,000  feet;  but  in  this  latter 
case  a  great  amount  of  the  thickness  is  made  up  of  volcanic 
ashes    and    interbedded    traps.     The    sedimentary   beds    of    this 
group    are    principally    slates    and   flags,    the    latter   occasionally 
with   calcareous   bands;    and   the   whole   series   can   be    divided 
into   a  lower,   middle,   and   upper .  Llandeilo   division,   of   which 
the  last  is  the  most  important.     The  name  of  "  Llandeilo "  is 
derived  from  the  town  of  the  same  name  in  Wales,  where  strata 
of  this  age  were  described  by  Murchison. 

3.  The  Caradoc  or  Bala  Group. — The  alternative  names  of 
this  group   are   also  of   local   origin,   and  are  derived,   the  one 


94  HISTORICAL  PALEONTOLOGY. 

from  Caer  Caradoc  in  Shropshire,  the  other  from  Bala  in  Wales, 
strata  of  this  age  occurring  in  both  localities.  The  series  is 
divided  into  a  lower  and  upper  group,  the  latter  chiefly  com- 
posed of  shales  and  flags,  and  the  former  of  sandstones  and 
shales,  together  with  the  important  and  interesting  calcareous 
band  known  as  the  "  Bala  Limestone. "  The  thickness  of  the 
entire  series  varies  from  4000  to  as  much  as  12,000  feet,  ac- 
cording as  it  contains  more  or  less  of  interstratified  igneous 
rocks. 

4.  The  Llandovery  Group  (Lower  Llandovery  of  Murchi- 
son). — This  series,  as  developed  near  the  town  of  Llandovery,  in 
Caermarthenshire,  consists  of  less  than  1000  feet  of  conglom- 
erates, sandstones,  and  shales.  It  is  probable,  however,  that 
the  little  calcareous  band  known  as  the  "  Hirnant  Limestone, " 
together  with  certain  pale-colored  slates  which  lie  above,  the 
Bala  Limestone,  though  usually  referred  to  the  Caradoc  series, 
should  in  reality  be  regarded  as  belonging  to  the  Llandovery 
group. 

The  general  succession  of  the  Lower  Silurian  strata  of 
Wales  and  its  borders,  attaining  a  maximum  thickness  (along 
with  contemporaneous  igneous  matter)  of  nearly  30,000  feet,  is 
diagramatically  represented  in  the  annexed  sketch-section  (fig. 
34):- 


[  GENERALIZED  SECTION 


THE  LOWER  SILURIAN  PERIOD. 


95 


GENERALIZED  SECTION  OF  THE  LOWER  SILURIAN  ROCKS 
OF  WALES. 


Fig.  34- 


May  Hill  Sandstone 
(base  of  Upper  Silu- 
rian). 

Llandovery  Group. 


Upper  Bala. 

Lower  Bala. 

Upper  Llandeilo. 
Middle   Llandeilo. 
Lower  Llandeilo. 

Upper  Arenig. 

Middle    Arenig. 

f  Lower     Arenig     (Up- 
•I      per  Tremadoc 
[     Group). 

f  Tremadoc   Slates 
j      (Lower    Tremadoc 
Group). 


In  North  America,  both  in  the  United  States  and  in  Can- 
ada, the  Silurian  rocks  are  very  largely  developed,  and  may  be 
regarded  as  constituting  an  exceedingly  full  and  typical  series 


96  HISTORICAL  PALEONTOLOGY. 

of  the  deposits  of  this  period.  The  chief  groups  of  the  Silurian 
rocks  of  North  America  are  as  follows,  beginning,  as  before, 
with  the  lowest  strata,  and  proceeding  upwards  (fig.  35)  : — 

1.  Quebec  Group. — This  group  is  typically  developed  in  the 
vicinity    of    Quebec,    where    it    consists    of    about    5000    feet    of 
strata,     chiefly    variously-colored     shales,     together     with     some 
sandstones  and  a  few  calcareous  bands.     It  contains  a  number 
of  peculiar   Graptolites,  by  which   it  can   be   identified   without 
question  with  the  Arenig  group  of  Wales  and  the  correspond- 
ing Skiddaw  Slates  of  the  North  of  England.     It  is  also  to  be 
noted  that  numerous   Trilobites   of   a   distinct   Cambrian   fades 
have    been    obtained    in    the    limestones    of    the    Quebec    group, 
near    Quebec.      These    fossils,    however,    have    been    exclusively 
obtained  from  the  limestones  of  the  group;  and  as  these  lime- 
stones   are    principally    calcareous    breccias    or    conglomerates, 
there   is    room    for   believing   that    these   primordial    fossils    are 
really  derived,  in  part  at  any  rate,  from  fragments  of  an  upper 
Cambrian  limestone.     In  the   State  of   New  York,  the   Grapto- 
litic  shales  of  Quebec  are  wanting;  and  the  base  of  the  Silurian 
is    constituted    by    the    so-called    "  Calciferous    Sand-rock"    and 
"  Chazy    Limestone. "  *      The    first    of    these    is    essentially    and 
typically  calcareous,  and  the  second  is  a  genuine  limestone. 

2.  The    Trenton    Group. — This    is    an    essentially   calcareous 
group,    the   various   limestones    of   which   it   is    composed   being 
known    as    the    "  Bird's-eye,  "    "  Black    River,  "    and    "  Trenton  " 
Limestones,  of  which  the  last  is  the  thickest  and  most  impor- 
tant.    The  thickness  of  this  group  is  variable,  and  the  bands  of 
limestone  in  it  are  often  separated  by  beds  of  shale. 

3.  The    Cincinnati    Group    (Hudson    River    Formation  f). — 
This  group  consists  essentially  of  a  lower  series  of  "shales,  often 
black    in    color    and    highly    charged    with    bituminous    matter 
(the  "  Utica  Slates"),  and  of  an  upper  series  of   shales,  sand- 
stones,  and  limestones    (the   "Cincinnati"   rocks   proper).     The 
exact  parallelism   of   the   Trenton   and   Cincinnati   groups   with, 

*  The  precise  relations  of  the  Quebec  shales  with  Graptolites  (Levis 
Formation)  to  the  Calciferous  and  "Chazy  beds  are  still  obscure,  though 
there  seems  little  doubt  but  that  the  Quebec  Shales  are  superior  to  the 
Calciferous  Sand-rock. 

t  There  _is  some  difficulty  about  the  precise  nomenclature  of  this  group. 
It  was  originally  called  the  "  Hudson  River  Formation ;"  but  this  name 
is  inappropriate,  as  rocks  of  this  age  hardly  touch  anywhere  the  actual 
Hudson  River  itself,  the  rocks  so  called  formerly  being  now  known  to  be 
of  more  ancient  date.  There  is  also  some  want  of  propriety  in  the  name 
of  "  Cincinnati  Group,"  since  the  rocks  which  are  known  under  this  name 
in^  the  vicinity  _  of  Cincinnati  itself  are  the  representatives  of  the  Trenton 
Limestone,  Utica  Slates,  and  the  Old  Hudson  River  group,  inseparably 
united  in  what  used  to  be  called  the  "  Blue  Limestone  Series." 


THE  LOWER  SILURIAN  PERIOD. 


97 


the  subdivisions  of  the  Welsh  Silurian  series  can  hardly  be 
stated  positively.  Probably  no  precise  equivalency  exists; 
but  there  can  be  no  doubt  but  that  the  Trenton  and  Cincin- 
nati groups  correspond,  as  a  whole,  with  the  Llandeilo  and 
Caradoc  groups  of  Britain.  The  subjoined  diagrammatic 
section  (fig.  35)  gives  a  general  idea  of  the  succession  of  the 
Lower  Silurian  rocks  of  North  America  :  — 

GENERALIZED  SECTION  OF  THE  LOWER  SILURIAN  ROCKS 
OF  NORTH  AMERICA. 


Fig.  35- 


Medina  Sandstone  (base  of 
Upper   Silurian). 


—  Cincinnati  Group  proper. 

Utica  Slates. 
Trenton  Limestone. 

Black  River  Limestone. 
Bird's-eye    Limestone. 
Chazy  Limestone. 

| Quebec  Shales   (Levis  Beds), 

Calciferous   Sand-rock. 

—  Potsdam   Sandstone. 


98  HISTORICAL  PALEONTOLOGY. 

Of  the  life  of  the  Lower  Silurian  period  we  have  record  in  a 
vast  number  of  fossils,  showing  that  the  seas  of  this  period 
were  abundantly  furnished  with  living  denizens.  We  have, 
however,  in  the  meanwhile,  no  knowledge  of  the  land-surfaces 
of  the  period.  We  have  therefore  no  means  of  speculating 
as  to  the  nature  of  the  terrestial  animals  of  this  ancient  age, 
nor  is  anything  known  with  certainty  of  any  land-plants  which 
may  have  existed.  The  only  relics  of  vegetation  upon  which 
a  positive  opinion  can  be  expressed  belong  to  the  obscure 
group  of  the  "  Fucoids, "  and  are  supposed  to  be  the  remains 
of  sea-weeds.  Some  of  the  fossils  usually  placed  under  this 
head  are  probably  not  of  a  vegetable  nature  at  all,  but  others 


Fig.  36. — LicropJiycua  Ottawctensis,  a  "  Fucoid,"  from  the  Trenton  Limestone 
(Lower  Silurian)  of  Canada.    (After  Billings.) 

(fig.  36)  appear  to  be  unquestionable  plants.  The  true  affin- 
ities of  these,  however,  are  extremely  dubious.  All  that  can 
be  said  is,  that  remains  which  appear  to  be  certainly  vegetable, 


THE  LOWER  SILURIAN  PERIOD. 


99 


and  which  are  most  probably  due  to  marine  plants,  have  been 
recognized  nearly  at  the  base  of  the  Lower  Silurian  (Arenig), 
and  that  they  are  found  throughout  the  series  whenever  suitable 
conditions  recur. 

The  Protozoans  appear  to  have  flourished  extensively  in  the 
Lower  Silurian  seas,  though  to  a  large  extent  under  forms 
which  are  still  little  understood.  We  have  here  for  the  first 
time  the  appearance  of  Foraminifera  of  the  ordinary  type — one 
of  the  most  interesting  observations  in  this  connection  being 
that  made  by  Ehrenberg,  who  showed  that  s  the  lower  Silurian 
sandstones  of  the  neighborhood  of  St.  Petersburg  contained 
casts  in  glauconite  of  Foraminiferous  shells,  some  of  which  are 
referable  to  the  existing  genera  Rotalia  and  Textularia.  True 
Sponges,  belonging  to  that  section  of  the  group  in  which  the 
skeleton  is  calcareous,  are  also  not  unknown,  one  of  the  most 

characteristic  genera  being  As- 
tylospongia  (fig.  37).  In  this 
genus  are  included  more  or  less 
globular,  often  lobed  sponges, 
which  are  believed  not  to  have 
been  attached  to  foreign  bodies. 
In  the  form  here  figured  there 
is  a  funnel-shaped  cavity  at  the 
summit ;  and  the  entire  mass  of 
the  sponge  is  perforated,  as  in 
living  examples,  by  a  system 
of  canals  which  convey  the 
sea-water  to  all  parts  of  the 
prcemona,  cut  organism.  The  canals  by 
which  the  sea-water  gains  en- 
Tennessee.  (After  Ferdinand  Rceiner.)  trance  open  on  the  exterior  of 

the  sphere,  and  those  by  which 

it  again  escapes  from  the  sponge  open  into  the  cup-shaped 
depression  at  the  summit. 

The  most  abundant,  and  at  the  same  time  the  least  under- 
stood, of  Lower  Silurian  Protozoans  belonging,  however,  to  the 
genera.  Stromatopora  and  Receptaculites,  the  structure  of  which 
can  merely  be  alluded  to  here.  The  specimens  of  Stromato- 
pora (fig.  38)  occur  as  hemispherical,  pear-shaped,  globular,  or 
irregular  masses,  often  of  very  considerable  size,  and  some- 
times demonstrably  attached  to  foreign  bodies.  In  their  struc- 
ture these  masses  consist  of  numerous  thin  calcareous  laminae, 
usually  arranged  concentrically,  and  separated  by  narrow 


ioo  HISTORICAL  PALEONTOLOGY. 

interspaces.        These     interspaces     are     generally     crossed     by 
numerous  vertical  calcareous  pillars,  giving  the  vertical  section 


Fig.  38 — A  small  and  perfect  specimen  of  Stromatopora  rugosa,  of  the  natural 
size,  from  the  Trenton  Limestone  of  Canada.     (After  Billings.) 

of  the  fossil  a  lattice-like  appearance.  There  are  also  usually 
minute  pores  in  the  concentric  laminae,  by  which  the  successive 
interspaces  are  placed  in  communication;  and  sometimes  the 
surface  presents  large  rounded  openings,  which  appear  to  corre- 
spond with  the  water-canals  of  the  Sponges.  Upon  the  whole, 
though  presenting  some  curious  affinities  to  the  calcareous 
Sponges,  Stromatopora  is  perhaps  more  properly  regarded  as 
a  gigantic  Foraminifer.  If  this  view  be  correct,  it  is  of  special 
interest  as  being  probably  the  nearest  ally  of  Eozoon,  the 
general  appearance  of  the  two  being  strikingly  similar,  though 
their  minute  structure  is  not  at  all  the  same.  Lastly,  in  the 
fossils  known  as  Receptaculites  and  Ischadites  we  are  also  pre- 
sented with  certain  singular  Lower  Silurian  Protozoans,  which 
may  with  great  probability  be  regarded  as  gigantic  Foraminif- 
era.  Their  structure  is  very  complex;  but  fragments  are 
easily  recognized  by  the  fact  that  the  exterior  is  covered  with 
numerous  rhomboidal  calcareous  plates,  closely  fitting  together, 
and  arranged  in  peculiar  intersecting  curves,  presenting  very 
much  the  appearance  of  the  engine-turned  case  of  a  watch. 


THE  LOWER  SILURIAN  PERIOD.  101 

Passing  next  to  the  sub-kingdom  of  Ccelenterate  animals 
(Zoophytes,  Corals,  &c.),  we  find  that  this  great  group,  almost 
or  wholly  absent  in  the  Cambrian,  is  represented  in  Lower 
Silurian  deposits  by  a  great  number  of  forms  belonging  on  the 
one  hand  to  the  true  Corals,  and  on  the  other  hand  to  the 
singular  family  of  the  Graptolites.  If  we  except  certain  plant- 
like  fossils  which  probably  belong  rather  to  the  Sertularians 
or  the  Polyzoans  (e.g.,  Dictyonema,  Dendrograptus,  &c.)>  the 
family  of  the  Graptolites  may  be  regarded  as  exclusively 
Silurian  in  its  distribution.  Not  only  is  this  the  case,  but  it 
attained  its  maximum  development  almost  upon  its  first  ap- 
pearance, in  the  Arenig  Rocks ;  and  whilst  represented  by  a 
great  variety  of  types  in  the  Lower  Silurian,  it  only  exists  in 
the  Upper  Silurian  in  a  much  diminished  form.  The  Grap- 
tolites (Gr.  grapho,  I  write;  lithos,  stone)  were  so  named  by 
Linnaeus,  from  the  resemblance  of  some  of  them  to  written  or 
pencilled  marks  upon  the  stone,  though  the  great  naturalist  him- 
self did  not  believe  them  to  be  true  fossils  at  all.  They  occur 
as  linear  or  tleaf-like  bodies,  sometimes  simple,  sometimes  com- 
pound and  branched;  and  no  doubt  whatever  can  be  enter- 
tained as  to  their  being  the  skeletons  of  composite  organisms, 
or  colonies  of  semi-independent  animals  united  together  by 
a  common  fleshy  trunk,  similar  to  what  is  observed  in  the 
colonies  of  the  existing  Sea-firs  (Sertularians).  This  fleshy 
trunk  or  common  stem  of  the  colony  was  protected  by  a  deli- 
cate horny  sheath,  and  it  gave  origin  to  the  little  flower-like 
"  polypites, "  which  constituted  the  active  element  of  the  whole 
assemblage.  These  semi-independent  beings  were,  in  turn, 
protected  each  by  a  little  horny  cup  or  cell,  directly  connected 
with  the  common  sheath  below,  and  terminating  above  in  an 
opening  through  which  the  polypite  could  protrude  its  tentacled 
head  or  could  again  withdraw  itself  for  safety.  The  entire 
skeleton,  again,  was  usually,  if  not  universally,  supported  by 
a  delicate  horny  rod  or  "  axis, "  which  appears  to  have  been 
hollow,  and  which  often  protrudes  to  a  greater  or  less  extent 
beyond  one  or  both  of  the  extremities  of  the  actual  colony. 

The  above  gives  the  elementary  constitution  of  any  Grapto- 
lite,  but  there  are  considerable  differences  as  to  the  manner  in 
which  these  elements  are  arranged  and  combined.  In  some 
forms  the  common  stem  of  the  colony  gives  origin  to  but  a 
single  row  of  cells  on  one  side.  If  the  common  stem  is  a 
simple,  straight,  or  slightly-curved  linear  body,  then  we  have 
the  simplest  form  of  Graptolite  known  (the  genus  Monograptus}  ; 


102  HISTORICAL  PALEONTOLOGY. 

and  it  is  worthy  of  note  that  these  simple  types  do  not  come 
into  existence  till  comparatively  late  (Llandeilo),  and  last 
nearly  to  the  very  close  of  the  Upper  Silurian.  In  other 
cases,  whilst  there  is  still  but  a  single  row  of  cells,  the  colony 
may  consist  of  two  of  these  simple  stems  springing  from  a 
common  point,  as  in  the  so-called  "  twin  Graptolites "  (Didy- 
mograptus,  fig.  40).  This  type  is  entirely  confined  to  the  earlier 

portion  of  the  Lower  Silu- 
rian period  (Arenig  and 
Llandeilo).  In  other  cases, 
again,  there  may  be  four 
of  such  stems  springing 
from  a  central  point.  (Tet- 
ragraptus).  Lastly,  there 
are  numerous  complex 
forms  (such  as  Dichograp- 
tus,  Loganograptus,  &c.)  in 
which  there  are  eight  or 
more  of  these  simple  bran- 
ches, all  arising  from  a 
common  center  (fig.  39), 
which  is  sometimes  fur- 
nished with  a  singular 
horny  disc.  These  com- 
plicated branching  forms, 
as  well  as  the  Tetragrapti, 
are  characteristic  of  the 
horizon  of  the  Arenig 
group.  Similar  forms,  of- 
ten specifically  identical, 


Fig.  39. — Dichograptus  octobracMatus,'&  branched,  "unicellular"  Grapto/lte  from 
the  Skiddaw  and  Quebec  Groups  (Arenig).    (After  Hall.) 

are  found  at  this  horizon  in  Wales,  in  the  great  series  of  the 
Skiddaw  Slates  of  the  north  of  England,  in  the  Quebec  group 
in  Canada,  in  equivalent  beds  in  Sweden,  and  in  certain  gold- 
bearing  slates  of  the  same  age  in  Victoria  in  Australia. 


THE  LOWER  SILURIAN  PERIOD. 


103 


In  another  great  group  of  Graptolites  (including  the  genera 
Diplograptus,  Dicranograptus,  Climacograptus,  &c.)  the  common 
stem  of  the  colony  gives  origin,  over  part  or  the  whole  of  its 


Fig.  40.— Central  portion  of  the  colony  of  Didymograptus  divaricatus,  Upper 
Llandeilo,  Dumfriesshire.     (Original.) 

length,  to  two  rows  of  cells,  one  on  each  side  (fig.  41).     These 
"  double-celled "    Graptolites    are    highly    characteristic    of    the 


Fig.  41.  — Examples    of    Diplograptus  Fig.  42.— Group  of  individuals  of  Phyllo- 

prtetis,  showing  variations  in  the  append-  graptus  typus,  from  the  Quebec  group  of 

ages    at    the   base.      Upper   Llandeilo,  Canada.  (After  Hall.)  One  of  the  four  rows 

Dnmfreisshire.    (Original.)  of  cells  is  hidden  on  the  under  surface. 

Lower   Silurian   deposits;   and,  with  an   exception  more  appar- 


104  HISTORICAL  PALEONTOLOGY. 

ent  than  real  in  Bohemia,  they  are  exclusively  confined  to 
strata  of  Lower  Silurian  age,  and  are  hot  known  to  occur  in 
the  Upper  Silurian.  Lastly,  there  is  a  group  of  Graptolites 
(Phyllograptus,  fig.  42)  in  which  the  colony  is  leaf-like  in  form, 
and  is  composed  of  four  rows  of  cells  springing  in  a  cross-like 
manner  from  the  common  stem.  These  forms  are  highly  char- 
acteristic of  the  Arenig  group. 

The  Graptolites  are  usually  found  in  dark-colored,  often 
black  shales,  which  sometimes  contain  so  much  carbon  as  to 
become  "  anthracitic. "  They  may  be  simply  carbonaceous ; 
but  they  are  more  commonly  converted  into  iron-pyrites,  when 
they  glitter  with  the  brilliant  luster  of  silver  as  they  lie  scattered 
on  the  surface  of  the  rock,  fully  deserving  in  their  metallic 
tracery  the  name  of  "  written  stones. "  They  constitute  one 
of  the  most  important  groups  of  Silurian  fossils,  and  are  of  the 
greatest  value  in  determining  the  precise  stratigraphical  posi- 
tion of  the  beds  in  which  they  occur.  They  present,  however, 
special  difficulties  in  their  study;  and  it  is  still  a  moot  point  as 
to  the  precise  position  in  the  zoological  scale.  The  balance 
of  evidence  is  in  favor  of  regarding  them  as  an  ancient  and 
peculiar  group  of  the  Sea-firs  (Hydroid  Zoophytes),  but  some 
regard  them  as  belonging  rather  to  the  Sea-mosses  (Polyzoa). 
Under  any  circumstances,  they  cannot  be  directly  compared 
either  with  the  ordinar}'  Sea-firs  or  the  ordinary  Sea-mosses ; 
for  these  two  groups  consist  of  fixed  organisms,  whereas  the 
Graptolites  were  certainly  free-floating  creatures,  living  at 
large  in  the  open  sea.  The  only  Hydroid  Zoophytes  or  Poly- 
zoans  which  have  a  similar  free  mode  of  existence,  have  either 
no  skeleton  at  all,  or  have  hard  structures  quite  unlike  the 
horny  sheaths  of  the  Graptolites. 

The  second  great  group  of  Coelenterate  animals  (Actinozoa} 
is  represented  in  the  Lower  Silurian  rocks  by  the  numerous 
Corals.  These,  for  obvious  reasons,  are  much  more  abundant 
in  regions  where  the  Lower  Silurian  series  is  largely  calcareous 
(as  in  North  America)  than  in  districts  like  Wales,  where 
limestones  are  very  feebly  developed.  The  Lower  Silurian 
Corals,  though  the  first  of  their  class,  and  presenting  certain 
peculiarities,  may  be  regarded  as  essentially  similar  in  nature 
to  existing  Corals.  These,  as  is  well  known,  are  the  calcareous 
skeletons  of  animals  —  the  so-called  "  Coral  -  Zoophytes  " — 
closely  allied  to  the  common  Sea-anemones  in  structure  and 
habit.  A  simple  coral  (fig.  43)  consists  of  a  calcareous  cup 
embedded  in  the  soft  tissues  of  the  flower-like  polype,  and  hav- 


THE  LOWER  SILURIAN  PERIOD. 


105 


ing  at  its  summit  a  more  or  less  deep  depression  (the  "calice") 
in  which  the  digestive  organs  are  contained.  The  space  within 
the  corals  is  divided  into  compartments  by  numerous  vertical 
calcareous  plates  (the  "septa"),  which  spring  from  the  inside 
of  the  wall  of  the  cup,  and  of  which  some  generally  reach  the 


Fig.  43.— Zaphrentls  Stokesi,  a  simple  Fig.  44.— Upper  surface  of  a  mass  of 
"  cup-coral,"  Upper  Silurian,  Canada.  Slrornbodes  pentagonus,  Upper  Silurian, 
(After  Billings.)  Canada.  (After  Billings.) 

center.  Compound  corals,  again  (fig.  44),  consist  of  a  greater 
or  less  number  of  structures  similar  inx  structure  to  the  above, 
but  united  together  in  different  ways  into  a  common  mass. 
Simple  corals,  therefore,  are  the  skeletons  of  single  and  inde- 
pendent polypes;  whilst  compound  corals  are  the  skeletons  of 
assemblages  or  colonies  of  similar  polypes,  living  united  with 
one  another  as  an  organic  community. 

In  the  general  details  of  their  structure,  the  Lower  Silurian 
Corals  do  not  differ  from  the  ordinary  Corals  of  the  present 
day.  The  latter,  however,  have  the  vertical  calcareous  plates 
of  the  coral  ("septa")  arranged  in  multiples  of  six  or  five; 
whereas  the  former  have  these  structures  arranged  in  multiples 
of  four,  and  often  showing  a  cross-like  disposition.  For  this 
reason,  the  common  Lower  Silurian  Corals  are  separated  to 
form  a  distinct  group  under  the  name  of  Rugose  Corals  or 
Rugosa.  They  are  further  distinguished  by  the  fact  that  the 
cavity  of  the  coral  ("visceral  chamber")  is  usually  subdivided 
by  more  or  less  numerous  horizontal  calcareous  plates  or 


io6  HISTORICAL  PALEONTOLOGY. 

partitions,  which  divide  the  coral  into  so  many  tiers  or  storeys, 
and  which  are  known  as  the  "  tabulae  "  (fig.  45). 

In  addition  to  the  Rugose  Corals,  the  Lower  Silurian  rocks 
contain  a  number  of  curious  compound  corals,  the  tubes 
of  which  have  either  no  septa  at  all  or  merely  rudimentary 
ones,  but  which  have  the  transverse  partitions  or  "  tabulae " 
very  highly  developed.  These  are  known  as  the  Tabulate 


Fig.  ±5.—Columnaria  alveolata,  a  Rugose  compound  coral,  with  Imperfect  septa,  but 
having  the  corallites  partitioned  off  into  storeys  by  "tabulae."  Lower  Silurian, 
Canada.  (After  Billings . ) 

Corals;  and  recent  researches  on  some  of  their  existing  allies 
(such  as  Helioporajhave  shown  that  they  are  really  allied  to 
the  modern  Sea-pens,  Organ-pipe  Corals,  and  Red  Coral, 
rather  than  to  the  typical  stony  Corals.  Amongst  the  charac- 
teristic Rugose  Corals  of  the  Lower  Silurian  may  be  mentioned 
species  belonging  to  the  genera  Columnaria,  Favistella,  Strep- 
telasma,  and  Zaphrentis;  whilst  amongst  the  "  Tabulate " 
Corals,  the  principal  forms  belong  to  the  genera  Chatetes, 
Halysites  (the  Chain-coral),  Constellaria,  and  Heliolites.  These 
groups  of  the  Corals,  however,  attain  a  greater  development 
at  a  later  period,  and  they  will  be  noticed  more  particularly 
hereafter. 

Passing  on  to  higher  animals,  we  find  that  the  class  of  the 
Echinodermata  is  represented  by  examples  of  the  Star-fishes 
(Asteroidea),  the  Sea-lilies  (Crinoidea},  and  the  peculiar  extinct 
group  of  the  Cystideans  (Cystoidea},  with  one  or  two  of  the 
Brittle-stars  (Ophiuroidea} — the  Sea-urchins  (Echinoidea}  being 
still  wanting.  The  Crinoids,  though  in  some  places  extremely 
numerous,  have  not  the  varied  development  that  they  possess 
in  the  Upper  Silurian,  in  connection  with  which  their  structure 
will  be  more  fully  spoken  of.  In  the  meanwhile,  it  is  sufficient 


THE  LOWER  SILURIAN  PERIOD. 


107 


to  note  that  many  of  the  calcareous  deposits  of  the  Lower 
Silurian  are  strictly  entitled  to  the  name  of  "  Crinoidal  lime- 
stones, "  being  composed  in  great  part  of  the  detached  joints, 


Fig.  46.— Group  of  Cystideans.  A,  Caryocrinus  ornatus*  Upper  Silurian,  America; 
B,  Pleurocystites  squamosus,  showing  two  short  "  arms,"  Lower  Silurian,  Canada;  C, 
Pseudocrinm  bifasciatua,  Upper  Silurian,  England;  D,  Lepadocrinus  Gebhardi, 
Upper  Silurian,  America.  (After  Hall,  Billings  and  Salter.) 

and  plates,  and  broken  stems,  of  these  beautiful  but  fragile 
organisms  (see  fig.  12).  Allied  to  the  Crinoids  are  the  singular 
creatures  which  are  known  as  Cystideans  (fig.  46).  These  are 
generally  composed  of  a  globular  or  ovate  body  (the  "calyx"), 
supported  upon  a  short  stalk  (the  "column"),  by  which  the 
organism  was  usually  attached  to  some  foreign  body.  The 
body  was  enclosed  by  closely-fitting  calcareous  plates,  accu- 
rately jointed  together;  and  the  stem  was  made  up  of  numerous 
distinct  pieces  or  joints,  flexibly  united  to  each  other  by  mem- 
brane. The  chief  distinction  which  strikes  one  in  comparing 
the  Cystideans  with  the  Crinoids  is,  that  the  latter  are  always 
furnished,  as  will  be  subsequently  seen,  with  a  beautiful  crown 
of  branched  and  feathery  appendages,  springing  from  the  sum- 

*  The  genus  Caryocrinus  is  sometimes  regarded  as  properly  belonging 
to  the  Crinoids,  but  there  seem  to  be  good  reasons  for  rather  considering 
it  as  an  abnormal  form  of  Cystidean.  • 


io8 


HISTORICAL  PALAEONTOLOGY. 


mit  of  the  calyx,  and  which  are  composed  of  innumerable 
calcareous  plates  or  joints,  and  are  known  as  the  "  arms.  "  In 
the  Cystideans,  on  the  other  hand,  there  are  either  no  "  arms " 
at  all,  or  merely  short,  unbranched,  rudimentary  arms.  The 
Cystideans  are  principally,  and  indeed  nearly  exclusively, 


Fig.  47.— Lower  Silurian  Crustaceans,  a,  Asaphus  tyrannus.  Upper  Llandeilo  ;  6. 
Ogygia  Buchii,  Upper  Llandeilo  ;  c,  Trinucleus  concentricus,  Caradoc  ;  d,  Caryocaris 
Wrigfitii,  Arenig  (Skiddaw  Slates) ;  e,  Beyrichia  complicata,  natural  size  and  enlarged, 
Upper  Llandeilo  and  Caradoc  ;  /,  Primitia  strangulata,  Caradoc  ;  g,  Head-shield  of 
Calymene  Blumenbachii,  var.  brevicapitata,  Caradoc  ;  h,  Head-shield  of  Triarthrm 
Becki  (Utica  Slates),  United  States  ;  i,  Shield  of  LeperdiUa  Canadensis,  var.  Joseph- 
iana,  of  the  natural  size,  Trenton  Limestone,  Canada;  j,  The  same,  viewed  from  the 
front.  (After  Salter,  M'Coy,  Rupert  Jones,  and  Dana.) 

Silurian  fossils ;  and  though  occurring  in  the  Upper  Silurian 
in  no  small  numbers,  they  are  pre-eminently  characteristic  of 
the  Llandeilo-Caradoc  period  of  Lower  Silurian  time.  They 


THE  LOWER  SILURIAN  PERIOD. 


105 


commenced  their  existence,  so  far  as  known,  in  the  Upper 
Cambrian ;  and  though  examples  are  not  absolutely  unknown 
in  later  periods,  they  are  pre-eminently  characteristic  of  the 
earlier  portion  of  the  Palaeozoic  epoch. 

The  Ringed  Worms  (Annelides}  are  abundantly  represented 
in  the  Lower  Silurian,  but  principally  by  tracks  and  burrows 
similar  in  essential  respects  to  those  which  occur  so  commonly 
in  the  Cambrian  formation,  and  calling  for  no  special  com- 
ment. Much  more  important  are  the  Articulate  animals,  rep- 
resented, as  heretofore,  wholly  by  the  remains  of  the  aquatic 
group  of  the  Crustaceans.  Amongst  these  are  numerous  little 
bivalved  forms — such  as  species  of  Primitia  (fig.  47  /),  Bey- 
richia  (fig.  47,  e),  and  Leperditia  (fig.  47,  i  and  /).  Most  of 
these  are  very  small,  varying  from  the  size  of  a  pin's  head  up 
to  that  of  a  hemp  seed;  but  they  are  sometimes  as  large  as 
a  small  bean  (fig.  47,  0,  and  they  are  commonly  found  in 
myriads  together  in  the  rock.  As  before  said,  they  belong  to 
the  same  great  group  as  the  living  Water-fleas  (Ostracoda). 
Besides  these,  we  find  the  pod-shaped  head-shields  of  the 
shrimp-like  Phyllopods — such  as  Caryocaris  (fig.  47,  d)  and 
Ceratiocaris.  More  important,  however,  than  any  of  these  are 
the  Trilobites,  which  may  be  considered  as  attaining  their  maxi- 


Fig.  48. — Ptilodictya  falciformis.  a, 
Small  specimen  of  the  natural  size  ;  6, 
Cross-section,  showing  the  shape  of  the 
front ;  c.  Portion  of  the  surface,  en- 
larged, Trenton  Limestone  and  Cincin- 
nati Group,  America.  (Original.) 


Fig.  49.— A,  Ptilodictya  acuta  ;  B,  Ptil- 
odictya Schafferi.  or,  Fragment,  of  the 
natural  size  ;  6,  portion,  enlarged  to 
show  the  cells.  Cincinnati  Group  of  Ohio 
and  Canada.  (Original.) 


mum  development  in  the  Lower  Silurian.  The  huge  Paradoxides 
of  the  Cambrian  have  now  disappeared,  and  with  them  almost 
all  the  principal  and  characteristic  "  primordial "  genera,  save 
Olenus  and  Agnostus.  In  their  place  we  have  a  great  number 


110 


HISTORICAL  PALEONTOLOGY. 


of  new  forms — some  of  them,  like  the  great  Asaphus  tyrannus 
of  the  Upper  Llandeilo  (fig.  47,  a),  attaining  a  length  of  a  foot 
or  more,  and  thus  hardly  yielding  in  the  matter  of  size  to  their 
ancient  'rivals.  Almost  every  subdivision  of  the  Lower  Silurian 
series  has  its  own  special  and  characteristic  species  of  Trilq- 
bites;  and  the  study  of  these  is  therefore  of  great  importance 
to  the  geologist.  A  few  widly-dispersed  and  characteristic 


Fig.  50.— Lower  Silurian  Brachiopods.  a.  and  a'  Orthis  biforata,  Llandeilo-Cara- 
doc,  Britain  and  America  ;  6,  Orthis  Jlabellulum,  Caradoc,  Britain  ;  c,  Orthia  sub- 
quadrata,  Cincinnati  Group,  America  ;  c'  Interior  of  the  dorsal  valve  of  the  same  ;  d, 
Strophomena  deltoidea,  Llandeilo-Caradoc,  Britain  and  America.  (After  Meek,  Hall, 
andSalter.) 

species  have  been  here  figured  (fig.  47)  ;  and  the  following 
may  be  considered  as  the  principal  Lower  Silurian  genera — 
Asaphus,  Ogygia,  Cheirurus,  Awipyx,  Calymene,  Trinucleus, 
Lichas,  Illanus,  JEglina,  Harpes,  Remopleurides,  Phacops, 
Acidaspis,  and  Homalonotus,  a  few  of  them  passing  upwards 
under  new  forms  into  the  Upper  Silurian. 

Coming  next  to  the  Mollusca,  we  find  the  group  of  the  Sea- 
mosses  and  Sea-mats  (Polyzoa}  represented  now  by  quite  a 
number  of  forms.  Amongst  these  are  examples  of  the  true 
Lace-corals  (Retepora  and  Fenestella},  with  their  netted  fan-like 
or  funnel-shaped  fronds ;  and  along  with  these  are  numerous 
delicate  encrusting  forms,  which  grew  parasitically  attached  to 
shells  and  corals  (Hippothoa,  Alecto,  &c.)  ;  but  perhaps  the 
most  characteristic  forms  belong  to  the  genus  Ptilodictya  (figs. 
48  and  49).  In  this  group  the  frond  is  flattened,  with  thin 


THE  LOWER  SILURIAN  PERIOD. 


in 


striated  edges,  sometimes  sword-like  or  scimitar-shaped,  but 
often  more  or  less  branched ;  and  it  consists  of  two  layers  of 
cells,  separated  by  a  delicate  membrane,  and  opening  upon 
opposite  sides.  Each  of  these  little  chambers  or  "  cells "  was 
originally  tenanted  by  a  minute  animal,  and  the  whole  thus 
constituted  a  compound  organism  or  colony. 

The  Lamp-shells  or  Brachiopods  are  so  numerous,  and  pre- 
sent such  varied  types,  both  in  this  and  the  succeeding  period 
of  the  Upper  Silurian,  that  the  name  of  "  Age  of  Brachiopods " 
has  with  justice  been  applied  to  the  Silurian  period  as  a  whole. 
It  would  be  impossible  here  to  enter  into  details  as  to  the 
many  different  forms  of  Brachiopods  which  present  themselves 
in  the  Lower  Silurian  deposits ;  but  we  may  select  the  three 
genera  Orthis,  Strophotnena,  and  Leptana  for  illustration,  as 
being  specially  characteristic  of  this  period,  though  not  exclu- 
sively confined  to  it.  The  numerous  shells  which  belong  to 
the  extensive  and  cosmopolitan  genus  Orthis  (fig.  50,  a,  b,  c, 


Fig.  51. — Lower  Silurian  Brachiopods.  a,  Strophomena  alternata,  Cincinnati  Group, 
America;  b,  Strophomena  JiliteMa,  Trenton  and  Cincinnati  Groups,  America  ;  c-,  Or- 
this tf,8tudinaria,  Caradoc,  Europe,  and  America  ;  d,  d',  Orthis  plicatella,  Cincinnati 
Group,  America  ;  e,  e1,  ef',  Leptcena  sencea,  Llandeilo  and  Caradoc,  Europe  and 
America.  (After  Meek,  Hall,  and  the  Author.) 

and  fig.  51,  c  and  rf),  are  usually  more  or  less  transversely- 
oblong  or  subquadrate,  the  two  valves  (as  more  or  less  in  all 
the  Brachiopods)  of  unequal  sizes,  generally  more  or  less  con- 
vex, and  marked  with  radiating  ribs  or  lines.  The  valves  of 
the  shell  are  united  to  one  another  by  teeth  and  sockets,  and 
there  is  a  straight  hinge-line.  The  beaks  are  also  separated 
by  a  distinct  space  ("hinge-area"),  formed  in  part  by  each 
valve,  which  is  perforated  by  a  triangular  opening,  through 


112 


HISTORICAL  PALEONTOLOGY. 


which,  in  the  living  condition,  passed  a  muscular  cord  attach- 
ing the  shell  to  some  foreign  object.  The  genus  Strophomena 
(fig.  50,  d,  and  51,  a  and  fr)  is  very  like  Ortliis  in  general  char- 
acter; but  the  shell  is  usually  much  flatter,  one  or  other  valve 
often  being  concave,  the  hinge-line  is  longer,  and  the  aperture 
for  the  emission  of  the  stalk  of  attachment  is  partially  closed 
by  a  calcareous  plate.  In  Leptana,  again  (fig.  51,  #),  the  shell 
is  like  Strophomena  in  many  respects,  but  generally  compara- 
tively longer,  often  completely  semicircular,  and  having  one 
valve  convex  and  the  other  valve  concave.  Amongst  other 
genera  of  Brachiopods  which  are  largely  represented  in  the 
Lower  Silurian  rocks  may  be  mentioned  Lingula,  Crania, 
Discina,  Trematis,  Siphonotreta,  Acrotreta,  Rhynchonella,  and 
Athyris;  but  none  of  these  can  claim  the  importance  to  which 
the  three  previously-mentioned  groups  are  entitled. 

The  remaining  Lower  Silurian  groups  of  Mollusca  can  be 
but  briefly  glanced  at  here.  The  Bivalves  (Lamellibranchiata) 
find  numerous  representatives,  belonging  to  such  genera  as 
Modiolopsis,  Ctenodonta,  Orthonota,  Palczarca,  Lyrodesma,  Am- 
bonychia,  and  Cleidophorus.  The  Univalves  (Gasteropoda)  are 
also  very  numerous,  the  two  most  important  genera  being 
Murchisonia  (fig.  52)  and  Pleurotomaria.  In  both  these  groups 
the  outer  lip  of  the  shell  is  notched ;  but  the  shell 
in  the  former  is  elongated  and  turreted,  whilst  in 
the  latter  it  is  depressed.  The  curious  oceanic 
Univalves  known  as  the  Heteropods  are  also  very 
abundant,  the  principal  forms  belonging  to  Bel- 
lerophon  and  Maclurea.  In  the  former  (fig.  53) 
there  is  a  symmetrical  convoluted  shell,  like  that 
of  the  Pearly  Nautilus  in  shape,  but  without  any 
internal  partitions,  and  having  the  aperture  of- 
ten expanded  and  notched  behind.  The  species 
of  Maclurea  (fig.  54)  are  found  both  in  North 
America  and  in  Scotland,  and  are  exclusively 
confined  to  the  Lower  Silurian  period,  so  far 
as  known.  They  have  the  shell  coiled  into  a 
flat  spiral,  the  mouth  being  furnished  with  a 
very  curious,  thick,  and  solid  lid  or  "  opercu- 
lum.  "  The  Lower  Silurian  Pteropods,  or  "Wing- 
ed Snails,  "  are  numerous,  and  belong  prin- 
cipally to  the  genera  Theca,  Conularia,  and 
Tentaculites,  the  last-mentioned  of  these  often  being  extremely 
abundant  in  certain  strata. 


Tig.  52.—  Mur- 
chisoniagracili*, 
Trenton  Lime- 
stone, America. 
(After  Billings.) 


THE  LOWER  SILURIAN  PERIOD.  113 

Lastly,  the  Lower  Silurian  Rocks  have  yielded  a  vast  num- 
ber of  chambered  shells,  referable  to  animals  which  belong 
to  the  same  great  division  as  the  Cuttle-fishes  (the  Cephalo- 
poda), and  of  which  the  Pearly  Nautilus  is  the  only  living 
representative  at  the  present  day.  In  this  group  of  Cephalopods 
the  animal  possesses  a  well-developed  external  shell,  which  is 
divided  into  chambers  by  shelly  partitions  ("septa").  The 
animal  lives  in  the  last-formed  and  largest  chamber  of  the 


Fig.  53. — Different  views  of  Bellerophon  Argo,  Trenton  Limestone,  Canada. 
(After  Billings.) 

shell,  to  which  it  is  organically  connected  by  muscular  attach- 
ments. The  head  is  furnished  with  long  muscular  processes  or 
"  arms,  "  and  can  be  protruded  from  the  mouth  of  the  shell  at 
will,  or  again  withdrawn  within  it.  We  learn,  also,  from  the 
Pearly  Nautilus,  that  these  animals  must  have  possessed  two 
pairs  of  breathing  organs  or  "  gills ;  "  hence  all  these  forms  are 
grouped  together  under  the  name  of  the  "  Tetrabranchiate " 


Fig.  54. — Different  views  of  Machirea  crenulata,  Quebec  Group,  Newfoundland. 
(After  Billings. ) 

Cephalopods  (Gr.  tetra,  four;  branghia, gills).    On  the  other  hand, 
the    ordinary    Cuttle-fishes    and  •Calamaries    either    possess    an 
8 


H4 


HISTORICAL  PALEONTOLOGY. 


internal  skeleton,  or  if  they  have  an  external  shell,  it  is  not 
chambered ;  their  "  arms "  are  furnished  with  powerful  organs 
of  adhesion  in  the  form  of  suckers;  and  they  possess  only  a 
single  pair  of  gills.  For  this  last  reason  they  are  termed  the 
"  Dibranchiate  "  Cephalopods  (Gr.  dis,  twice ;  branghia,  gills).  No 
trace  of  the  true  Cuttle-fishes  has  yet  been  found  in  Lower 
Silurian  deposits;  but  the  Tetrabranchiate  group  is  represented 


Fig.  55. — Fragment  of  Orthoceras  cre- 
briseptum,  Cincinnati  Group,  North 
America,  of  the  natural  size.  The  lower 
figure  is  a  section  showing  the  air-cham- 
bers, and  the  form  and  position  of  the 
siphuncle.  (After  Billings.) 


Fig.  56. — Restoration  of  Orthoceraa, 
the  shell  being  supposed  to  be  divided 
vertically,  and  only  its  upper  part  being 
shown,  a,  Arms ;  /,  Muscular  tube 
("funnel")  by  which  water  is  expelled 
from  the  mantle-chamber ;  c,  Air-cham- 
bers ;  s,  Siphuncle. 


by  a  great  number  of  forms,  sometimes  of  great  size.  The  prin- 
cipal Lower  Silurian  genus  is  the  well-known  and  widely- 
distributed  Orthoceras  (fig.  55).  The  shell  in  this  genus  agrees 
with  that  of  the  existing  Pearly  Nautilus,  in  consisting  of  num- 

*  This  illustration  is  taken  from  a  rough  sketch  made  by  the  author 
many  years  ago,  but  he  is  unable  to  say  from  what  original  source  it  was 
copied. 


THE  LOWER  SILURIAN  PERIOD.  115 

erous  chambers  separated  by  shelly  partitions  (or  septa),  the 
latter  being  perforated  by  a  tube  which  runs  the  whole  length  of 
the  shell  after  the  last  chamber,  and  is  known  as  the  "  siphuncle  " 
(fig.  56,  j).  The  last  chamber  formed  is  the  largest,  and  in  it 
the  animal  lives.  The  chambers  behind  this  are  apparently  filled 
with  some  gas  secreted  by  the  animal  itself ;  and  these  are  sup- 
posed to  act  as  a  kind  of  float,  enabling  the  creature  to  move 
with  ease  under  the  weight  of  its  shell.  The  various  air- 
chambers,  though  the  siphuncle  passes  through  them,  have  no 
direct  connection  with  one  another ;  and  it  is  believed  that  the 
animal  has  the  power  of  slightly  altering  its  specific  gravity, 
and  thus  of  rising  or  sinking  in  the  water  by  driving  additional 
fluid  into  the  siphuncle  or  partially  emptying  it.  The  Ortho- 
ceras further  agrees  with  the  Pearly  Nautilus  in  the  fact  that 
the  partitions  or  septa  separating  the  different  air-chambers  are 
simple  and  smooth,  concave  in  front  and  convex  behind,  and 
devoid  of  the  elaborate  lobation  which  they  exhibit  in  the 
Ammonites;  whilst  the  siphuncle  pierces  the  septa  either  in 
the  center  or  near  it.  In  the  Nautilus,  however,  the  shell  is 
coiled  into  a  flat  spiral ;  whereas  in  Orthoceras  the  shell  is 
a  straight,  longer  or  shorter  cone,  tapering  behind,  and  gradu- 
ally expanding  towards  its  mouth  in  front.  The  chief  objec- 
tions to  the  belief  that  the  animal  of  the  Orthoceras  was  essen- 
tially like  that  of  the  Pearly  Nautilus  are — the  comparatively 
small  size  of  the  body-chamber,  the  often  contracted  aperture 
of  the  mouth,  and  the  enormous  size  of  some  specimens  of 
tjie  shell.  Thus,  some  Orthocerata  have  been  discovered 
measuring  ten  or  twelve  feet  in  length,  with  a  diameter  of  a 
foot  at  the  larger  extremity.  These  colossal  dimensions  cer- 
tainly make  it  difficult  to  imagine  that  the  comparatively  small 
body-chamber  could  have  held  an  animal  large  enough  to  move 
a  load  so  ponderous  as  its  own  shell.  To  some,  this  difficulty 
has  appeared  so  great  that  they  prefer  to  believe  that  the 
Orthoceras  did  not  live  in  its  shell  at  all,  but  that  its  shell  was 
an  internal  skeleton  similar  to  what  we  shall  find  to  exist  in 
many  of  the  true  Cuttle-fishes.  There  is  something  to  be  said 
in  favor  of  this  view,  but  it  would  compel  us  to  believe  in  the 
existence  in  Lower  Silurian  times  of  Cuttle-fishes  fully  equal 
in  size  to  the  giant  "  Kraken "  of  fable.  It  need  only  be 
added  in  this  connection  that  the  Lower  Silurian  rocks  have 
yielded  the  remains  of  many  other  Tetrabranchiate  Cephalo- 
pods  besides  Orthoceras.  Some  of  these  belong  to  Cyrtoceras, 


n6  HISTORICAL  PALAEONTOLOGY. 

which  only  differs  from  Orthoceras  in  the  bow-shaped  form  of 
the  shell ;  others  belong  to  Phragmoceras,  Lituites,  &c. ;  and, 
lastly,  we  have  true  Nautili,  with  their  spiral  shells,  closely 
resembling  the  existing  Pearly  Nautilus. 

Whilst  all  the  sub-kingdoms  of  the  Invertebrate  animals  are 
represented  in  the  Lower  Silurian  rocks,  no  traces  of  Verte- 
brate animals  have  ever  been  discovered  in  these  ancient 
deposits,  unless  the  so-called  "  Conodonts "  found  by  Pander 
in  vast  numbers  in  strata  of  this  age  *  in  Russia  should  prove 
to  be  really  of  this  nature.  These  problematical  bodies  are  of 
microscopic  size,  and  have  the  form  of  minute,  conical,  tooth- 
shaped  spines,  with  sharp  edges,  and  hollow  at  the  base. 
Their  original  discoverer  regarded  them  as  the  horny  teeth 
of  fish  allied  to  the  Lampreys ;  but  Owen  came  to  the  con- 
clusion that  they  probably  belonged  to  Invertebrates.  The 
recent  investigation  of  a  vast  number  of  similar  but  slightly 
larger  bodies,  of  very  various  forms,  in  the  Carboniferous  rocks 
of  Ohio,  has  led  Professor  Newberry  to  the  conclusion  that 
these  singular  fossils  really  are,  as  Pander  thought,  the  teeth  of 
Cyclostomatous  fishes.  The  whole  of  this  difficult  question 
has  thus  been  reopened,  and  we  may  yet  have  to  record  the 
first  advent  of  Vertebrate  animals  in  the  Lower  Silurian. 


CHAPTER  X. 
THE  UPPER  SILURIAN  PERIOD. 

Having  now  treated  of  the  Lower  Silurian  period  at  con- 
siderable length,  it  will  not  be  necessary  to  discuss  the  succeeding 
group  of  the  Upper  Silurian  in  the  same  detail — the  more  so, 
as  with  a  general  change  of  species  the  Upper  Silurian  animals 
belong  for  the  most  part  to  the  same  great  types  as  those  which 

*  According  to  Pander,  the  "  Conodonts  "  are  found  not  only  in  the 
Lower  Silurian  beds,  but  also  in  the  "  Ungulite  Grit  "  (Upper  Cambrian), 
as  well  as  in  the  Devonian  and  Carboniferous  deposits  of  Russia.  Should 
the  Conodonts  prove  to  be  truly  the  remains  of  fishes,  we  should  thus  have 
to  transfer  the  first  appearance  of  Vertebrates  to,  at  any  rate,  as  early  a 
period  as  the  Upper  Cambrian. 


THE  UPPER  SILURIAN  PERIOD.  117 

distinguish  the  Lower  Silurian.  As  compared,  also,  as  regards 
the  total  bulk  of  strata  concerned,  the  thickness  of  the  Upper 
Silurian  is  generally  very  much  below  that  of  the  Lower  Silurian, 
indicating  that  they  represent  a  proportionately  shorter  period 
of  time.  In  considering  the  general  succession  of  the  Upper 
Silurian  beds,  we  shall,  as  before,  select  Wales  and  America  as 
being  two  regions  where  these  deposits  are  typically  developed. 
In  Wales  and  its  borders  the  general  succession  of  the 
Upper  Silurian  rocks  may  be  taken  to  be  as  follows,  in  ascend- 
ing order  (fig.  57)  :— 

(1)  The  base  of  the  Upper  Silurian  series  is  constituted  by 
a  series  of  arenaceous  beds,  to  which  the  name  of  "  May  Hill 
Sandstone "    was    applied    by    Sedgwick.      These    are    succeeded 
by   a   series   of    greenish-grey   or    pale-grey    slates    ("Tarannon 
Shales"),  sometimes  of  great  thickness;  and  these  two  groups 
of   beds    together    form   what   may   be   termed   the    "May   Hill 
Group"    (Upper  Llandovery  of  Murchison).     Though  not  very 
extensively    developed    in    Britain,    this    zone   is    one    very    well 
marked   by   its    fossils ;    and   it   corresponds   with   the    "  Clinton 
Group "  of   North  America,  in  which  similar  fossils  occur.     In 
South  Wales  this  group  is  clearly  unconformable  to  the  highest 
member    of    the    subjacent    Lower    Silurian     (the    Llandovery 
group)  ;  and  there  is  a  reason  to  believe  that  a  similar,  though 
less  conspicuous,  physical   break  occurs  very  generally  between 
the  base  of  the  Upper  and  the  summit  of  the  Lower  Silurian. 

(2)  The  Wenlock  Group  succeeds  the  May  Hill  group,  and 
constitutes   the  middle   member  of   the  Upper   Silurian.     At  its 
base   it   may   have   an   irregular   limestone    ("  Woolhope    Lime- 
stone"), and  its  summit  may  be  formed  by  a  similar  but  thicker 
calcareous  deposit  ("Wenlock  Limestone")  ;  but  the  bulk  of  the 
group  is  made  up  of  the  argillaceous  and  shaly  strata  known  as 
the  "  Wenlock  Shale.  "     In  North  Wales  the  Wenlock  group  is 
represented  by  a  great  accumulation  of  flaggy  and  gritty  strata 
(the  "Denbighshire  Flags  and  Grits"),  and  similar  beds    (the 
"  Coniston  Flags"  and  "  Coniston  Grits")   take  the  same  place 
in  the  north  of  England. 

(3)  The  Ludlow  Group  is  the  highest  member  of  the  Upper 
Silurian,  and  consists  typically  of  a  lower  arenaceous  and  shaly 
series     (the    "Lower    Ludlow    Rock"),    a    middle    calcareous 
member   (the  "  Aymestry  Limestone"),  and  an  upper  shaly  and 
sandy  series  (the  "Upper  Ludlow  Rock"),  and  "  Downton  Sand- 
stone").   At  the  summit,  or  close  to  the  summit,  of  the  Upper 


n8        HISTORICAL  PALEONTOLOGY. 

Ludlow,  is  a  singular  stratum  only  a  few  inches  thick  (vary- 
ing from  an  inch  to  a  foot),  which  contains  numerous  remains 
of  crustaceans  and  fishes,  and  is  well  known  under  the  name 
of  the  "  bone-bed. "  Finally,  the  Upper  Ludlow  rock  graduates 
invariably  into  a  series  of  red  sandy  deposits,  which,  when  of 
a  flaggy  character,  are  known  locally  as  the  "  Tile-stones. " 
These  beds  are  probably  to  be  regarded  as  the  highest  member 
of  the  Upper  Silurian;  but  they  are  sometimes  looked  upon  as 
passage-beds  into  the  Old  Red  Sandstone,  or  as  the  base  of 
this  formation.  It  is,  in  fact,  apparently  impossible  to  draw 
any  actual  line  of  demarcation  between  the  Upper  Silurian  and 
the  overlying  deposits  of  the  Devonian  or  Old  Red  Sandstone 
series.  Both  in  Britain  and  in  America  the  Lower  Devonian 
beds  repose  with  perfect  conformity  upon  the  highest  Silurian 
beds,  and  the  two  formations  appear  to  pass  into  one  another 
by  gradual  and  imperceptible  transition. 

The  Upper  Silurian  strata  of  Britain  vary  from  perhaps 
3000  or  4000  feet  in  thickness  up  to  8000  or  10,000  feet.  In 
North  America  the  corresponding  series,  though  also  variable, 
is  generally  of  much  smaller  thickness,  and  may  be  under  1000 
feet.  The  general  succession  of  the  Upper  Silurian  deposits 
of  North  America  is  as  follows : — 

(1)  Medina  Sandstone. — This   constitutes   the   base   of   the 
Upper  Silurian,  and  consists  of  sandy  strata,  singularly  devoid 
of   life,    and   passing   below    in    some    localities    into    a    conglo- 
merate   ("  Oneida   Conglomerate"),   which   is   stated   to   contain 
pebbles    derived    from    the    older    beds,    and    which    would    thus 
indicate     an     unconformity     between     the     Upper     and     Lower 
Silurian. 

(2)  Clinton    Group. — Above    the     Medina    sandstone     are 
beds  of  sandstone  and  shale,  sometimes  with  calcareous  bands, 
which  constitute  what  is  known  as  the  "  Clinton  Group.  "     The 
Medina  and  Clinton  groups  are  undoubtedly  the   equivalent  of 
the  "  May  Hill  Group "  of  Britain,  as  shown  by  the  identity  of 
their  fossils. 

(3)  Niagara    Group. — This    group    consists    typically    of    a 
series    of    argillaceous    beds     ("Niagara    Shale")     capped    by 
limestone     ("Niagara    Limestone");     and    the    name    of    the 
group  is  derived  from  the  fact  that  it  is  over  limestones  of  this 
age   that  the   Niagara  river   is   precipitated   to    form   the   great 
Falls.      In    places    the    Niagara    group    is    wholly    calcareous, 
and  it  is  continued  upwards  into  a  series  of  marls  and  sand- 


THE  UPPER  SILURIAN  PERIOD. 


119 


GENERALIZED  SECTION  OF  THE  UPPER  SILURIAN  STRATA 
OF  WALES  AND  SHROPSHIRE. 

Fig.  57- 


Base  of  Old  Red  Sand- 
stone. 


~-  Pile-stones. 


Upper  Ludlow  Rock. 
Aymestry  Limestone. 

Lower  Ludlow  Rock. 
Wenlock  Limestone. 

f  Wenlock  Shale  (Den- 
]  bighshire  Flags  and 
[  Grits  of  North  Wales). 

Woolhope   Limestone. 
Tarannon   Shales. 
May  Hill  Sandstone. 


—  Llandovery  Rocks. 


stones,  with  beds  of  salt  and  masses  of  gypsum  (the  "  Salina 
Group"),  or  into  a  series  of  magnesian  limestones  ("Guelph 
Limestones").  The  Niagara  group,  as  a  whole,  corresponds 
unequivocally  with  the  Wenlock  group  of  Britain. 

(4)  Lower  Hcldcrbcrg  Group. — The  Upper  Silurian  period 
in  North  America  was  terminated  by  the  deposition  of  a  series 
of  calcareous  beds,  which  derive  the  name  of  "Lower  Helder- 
berg "  from  the  Helderberg  mountains,  south  of  Albany,  and 
which  are  divided  into  several  zones,  capable  of  recognition  by 
their  fossils,  and  known  by  local  names  (Tentaculite  Lime- 
stone, Water-lime,  Lower  Pentamerus  Limestone,  Delthyris 


120  HISTORICAL  PALEONTOLOGY. 

Shaly  Limestone,  and  Upper  Pentamerus  Limestone).  As  a 
whole,  this  series  may  be  regarded  as  the  equivalent  of  the 
Ludlow  group  of  Britain,  though  it  is  difficult  to  establish  any 
precise  parallelism.  The  summit  of  the  Lower  Helderberg 
group  is  constituted  by  a  coarse-grained  sandstone  (the  "  Oris- 
kany  Sandstone"),  replete  with  organic  remains,  which  have 
to  a  large  extent  a  Silurian  fades.  Opinions  differ  as  to  whether 
this  sandstone  is  to  be  regarded  as  the  highest  bed  of  the  Upper 
Silurian  or  the  base  of  the  Devonian.  We  thus  see  that  in 
,  America,  as  in  Britain,  no  other  line  than  an  artificial  one  can  be 
drawn  between  the  Upper  Silurian  and  the  overlying  Devonian. 

As  regards  the  life  of  the  Upper  Silurian  period,  we  have,  as 
before,  a  number  of  so-called  "  Fucoids, "  the  true  vegetable 
nature  of  which  is  in  many  instances  beyond  doubt.  In  addition 
to  these,  however,  we  meet  for  the  first  time,  in  deposits 
of  this  age,  with  the  remains  of  genuine  land-plants,  though 
our  knowledge  of  these  is  still  too  scanty  to  enable  us  to  con- 
struct any  detailed  picture  of  the  terrestrial  vegetation  of  the 
period.  Some  of  these  remains  indicate  the  existence  of  the 
remarkable  genus  Lepidodendron — a  genus  which  played  a  part 
of  great  importance  in  the  forests  of  the  Devonian  and  Carbon- 
iferous periods,  and  which  may  be  regarded  as  a  gigantic  and 
extinct  type  of  the  Club-mosses  (Lycopodiacece}.  Near  the 
summit  of  the  Ludlow  formation  in  Britain  there  have  also 
been  found  beds  charged  with  numerous  small  globular  bodies, 
which  Dr.  Hooker  has  shown  to  be  the  seed-vessels  or  "  spor- 
angia" of  Club-mosses.  Principal  Dawson  further  states  that 
he  has  seen  in  the  same  formation  fragments  of  wood  with  the 
structure  of  the  singular  Devonian  Conifer  known  as  Proto- 
taxites.  Lastly,  the  same  distinguished  observer  has  described 
from  the  Upper  Silurian  of  North  America  the  remains  of  the 
singular  land-plants  belonging  to  the  genus  Psilophyton,  which 
will  be  referred  to  at  greater  length  hereafter. 

The  marine  life  of  the  Upper  Silurian  is  in  the  main  con- 
stituted by  types  of  animals  similar  to  those  characterizing  the 
Lower  Silurian,  though  for  the  most  part  belonging  to  different 
species.  The  Protozoans  are  represented  principally  by  Stro- 
matopora  and  Ischadites,  along  with  a  number  of  undoubted 
sponges  (such  as  Amphispongia,  Astraospongia,  Astylospongia, 
and  Palteoman on ) . 

Amongst  the  Calenterates,  we  find  the  old  group  of  Grap- 
tolites  now  verging  on  extinction.  Individuals  still  remain 


THE  UPPER  SILURIAN  PERIOD. 


121 


B 


numerous,  but  the  variety  of  generic  and  specific  types  has 
now  become  greatly  reduced.  All  the  branching  and  complex 
forms  of  the  Arenig,  the  twin-Grap- 
tolites  and  Dicranograpti  of  the 
Llandeilo,  and  the  double-celled 
Diplograpti  and  Climacograpti  of 
the  Bala  group,  have  now  disap- 
peared. In  their  place  we  have 
the  singular  Retiolites^with  its  curi- 
ously-reticulated skeleton ;  and  sev- 
eral species  of  the  single-celled  genus 
Monograptus,oi  which  a  character- 
istic species  (M.  priodon)  is  here 
figured.  If  we  remove  from  this 
group  the  plant-like  Dictyonemee, 
which  are  still  present,  and  which 
survive  into  the  Devonian,  no 
known  species  of  Graptolite  has 
hitherto  been  detected  in  strata 
higher  in  geological  position  than 
the  Ludlow.  This,  therefore,  pre- 
sents us  with  the  first  instance  we 
have  as  yet  met  with  of  the  total 
disappearance  and  extinction  of  a 
great  and  important  series  of  or- 
ganic forms. 

The  Corals  are  very  numer- 
ously represented  in  the  Upper 
Silurian  rocks,  some  of  the  lime- 
stones (such  as  the  Wenlock  Lime- 
stone) being  often  largely  composed  of  the  skeletons  of  these 
animals.  Almost  all  the  known  forms  of  this  period  belong  to 
the  two  great  divisions  of  the  Rugose  and  Tabulate  corals,  the 
former  being  represented  by  species  of  Zaphrentis,  Omphyma, 
Cystiphyllum,  Strombodes,  Acervularia,  Cyathophyllum,  &c. ; 
whilst  the  later  belong  principally  to  the  genera  Favosites, 
Chatctes,  Halysites,  Syringopora,  Heliolites,  and  Plasmopora. 
Amongst  the  Rugosa,  the  first  appearance  of  the  great  and 
important  genus  Cyathophyllum,  so  characteristic  of  the  Palae- 
ozoic period,  is  to  be  noted;  and  amongst  the  Tabulata  we 
have  similarly  the  first  appearance,  in  force  at  any  rate,  of  the 
widely  -  spread  genus  Favosites  —  the  "  Honeycomb  -  corals.  " 
The  "  Chain-corals "  (Halysites},  figured  below  (fig.  59),  are. 


Fig.  58.— A,  Monograptus  prio- 
don,  slightly  enlarged.  B,  Frag- 
ment of  the  same  viewed  from  be- 
hind. C,  Fragment  of  the  same 
viewed  in  front,  showing  the 
mouths  of  the  cellules.  D,  Cross- 
section  of  the  same.  From  the 
Wenlock  Group  (Conlston  Flags  of 
the  North  of  England. )  (Original.) 


122 


HISTORICAL  PALEONTOLOGY. 


also  very  common  examples  of  the  Tabulate  corals  during  this 
period,  though  they  occur  likewise  in  the  Lower  Silurian. 

Amongst   the  Echinodermata,  all  those  orders   which   have 
hard    parts    capable    of    ready    preservation    are    more    or    less 


d 


Fig.  59.— a,  Haly sites  catenularia,  small  variety,  of  the  natural  size  ;  Fragment  of 
a  large  variety  of  the  same,  of  the  natural  size  ;  c,  Fragment  of  limestone  with  the 
tubes  of  ffalysites  agglomerata,  of  the  natural  size  ;  d,  Vertical  section  of  two  tubes 
of  the  same,  showing  the  tabulae,  enlarged.  Niagara  Limestone  (Wenlock),  Canada. 
(Original.) 

largely  represented.  We  have  no  trace  of  the  Holothurians 
or  Sea-cucumbers;  but  this  is  not  surprising,  as  the  record  of 
the  past  is  throughout  almost  silent  as  to  the  former  existence 
of  these  soft-bodied  creatures,  the  scattered  plates  and  spicules 
in  their  skin  offering  a  very  uncertain  chance  of  preservation 
in  the  fossil  condition.  The  Sea-urchins  (Echinoids)  are  said 
to  be  represented  by  examples  of  the  old  genus  Pal&chinus. 
The  Star-fishes  (Asteroids)  and  the  Brittle-stars  (Ophiuroids) 
are,  comparatively  speaking,  largely  represented,  the  former 
by  species  of  Palasterina  (fig.  60),  Palceaster  (fig.  60),  Palao- 
coma  (fig.  60),  Petr aster,  Gly 'piaster,  and  Lepidaster — and  the 
latter  by  species  of  Protaster  (fig.  61),  Palceodiscus,  Acroura, 
and  Eucladia.  The  singular  Cystideans,  or  "Globe  Crinoids, " 
with  their  globular  or  ovate,  tesselated  bodies  (fig.  46,  A,  C,  D,), 
are  also  not  uncommon  in  the  Upper  Silurian ;  and  if  they  do 
not  become  finally  extinct  here,  they  certainly  survive  the  close 


THE  UPPER  SILURIAN  PERIOD. 


123 


of  this  period  by  but  a  very  brief  time.     By  far  the  most  im- 
portant,  however,  of   the   Upper   Silurian   Echinoderms,"  are  the 


Fig.  60. — Upper  Silurian  Star-fishes.  1,  Palasterina  primceva-  Lower  Ludlow  ;  2, 
Palceaster  Ruthveni  Lower  Ludlow;  3,  Palceocoma  Colvini,  Lower  Ludlow.  (After 
Salter.) 

Sea-lilies  or  Crinoids.  The  Limestones  of  this  period  are  often 
largely  composed  of  the  fragmentary  columns  and  detached 
plates  of  these  creatures,  and  some  of  them  (such  as  the  Wen- 


rig.  61.— A,  Protaster  Sedgwickii,  showing  the  disc  and  bases  of  the  arms  ;  B,  Por- 
tion of  an  arm,  greatly  enlarged.    Lower  Ludlow.     (After  Salter. ) 

lock  Limestone  of  Dudley)  have  yielded  perhaps  the  most 
exquisitely-preserved  examples  of  this  group  with  which  we 
are  as  yet  acquainted.  However  varied  in  their  forms,  these 
beautiful  organisms  consists  of  a  globular,  ovate,  or  pear-shaped 
body  (the  "calyx"),  supported  upon  a  longer  or  shorter 
jointed  stem  (or  "column").  The  body  is  covered  externally 
with  an  armour  of  closely-fitting  calcareous  plates  (fig.  62),  and 
its  upper  surface  is  protected  by  similar  but  smaller  plates 


124 


HISTORICAL  PALEONTOLOGY. 


more  loosely  connected  by  a  leathery  integument.  From  the 
upper  surface  of  the  body,  round  its  margin,  springs  a  series 
of  longer  or  shorter  flexible  processes,  composed  of  innu- 
merable calcareous  joints  or  pieces,  movably  united  with  one 
another.  The  arms  are  typically  five  in  number;  but  they 
generally  subdivide  at  least  once,  sometimes  twice,  and  they 
are  furnished  with  similar  but  more  slender  lateral  branches 


Fig.  G2.— Upper  Silurian  Crinoids.  «,  Calyx  and  arms  of  Eucalyptocrinua  polydac- 
tylus,  Wenlock  Limestone  ;  b,  Ichthyocrinus  Icevis,  Niagara  Limestone,  America  ;  c, 
Taxocrinus  tuberculatus,  Wenlock  Limestone.  (After  M'Coy  and  Hall.) 


or  "  pinnules,  "  thus  giving  rise  to  a  crown  of  delicate  feathery 
plumes.  The  "  column "  is  the  stem  by  which  the  animal  is 
attached  permanently  to  the  bottom  of  the  sea;  and  it  is  com- 
posed of  numerous  separate  plates,  so  jointed  together  that 
whilst  the  amount  of  movement  between  any  two  pieces  must 
be  very  limited,  the  entire  column  acquires  more  or  less  flexi- 
bility, allowing  the  organism  as  a  whole  to  wave  backwards  and 
forwards  on  its  stalk.  Into  the  exquisite  minutice  of  structure 
by  which  the  innumerable  parts  entering  into  the  composition 
of  a  single  Crinoid  are  adapted  for  their  proper  purpose  in 
the  economy  of  the  animal,  it  is  impossible  to  enter  here.  No 
period,  as  before  said,  has  yielded  examples  of  greater  beauty 
than  the  Upper  Silurian,  the  principal  genera  represented 
being  Cyathocrinus,  Platycrinus,  Marsupiocrinus,  Taxocrinus, 


THE  UPPER  SILURIAN  PERIOD. 


125 


Eucalyptocrinus,  Ichthyocrinus,  Mariacrinus,  Periechocrinus, 
Glyptocrinus,  Crotalocrinus,  and  Edriocrinus. 

The  tracks  and  burrows  of  Annelides  are  as  abundant  in 
the  Upper  Silurian  strata  as  in  older  deposits,  and  have  just 
as  commonly  been  regarded  as  plants.  The  most  abundant 
forms  are  the  cylindrical,  twisted  bodies  (Planolites),  which  are 
so  frequently  found  on  the  surfaces  of  sandy  beds,  and  which 
have  been  described  as  the  stems  of  sea-weeds.  These  fossils 
(fig.  63),  however,  can  be  nothing  more,  in  most  cases,  than 
the  filled-up  burrows  of  marine  worms  resembling  the  living 
Lobe-worms.  There  are  also  various  remains  which  belong  to 
the  group  of  the  tube-inhabiting  Annelides  (Tubicola).  Of 
this  nature  are  the  tubes  of  Serpulites  and  Cornulites,  and  the 
little  spiral  discs  of  Spirorbis  Lewisii. 

Amongst  the  Articulates,  we  still  meet  only  with  the  remains 
of  Crustaceans.  Besides  the  little  bivalved  Ostracoda — which 
here  are  occasionally  found  of  the  size  of  beans — and  various 


Fig.  BS.—Planolites  vulgaris,  the  fllled-up  burrows  of  a  marine  worm. 
Upper  Silurian  (Clinton  Group),  Canada      (Original.) 

Phyllopods  of  different  kinds,  we  have  an  abundance  of  Trilo- 
bites.  These  last-mentioned  ancient  types,  however,  are  now 
beginning  to  show  signs  of  decadence;  and  though  still  indi- 


126 


HISTORICAL  PALAEONTOLOGY. 


vidually  numerous,  there  is  a  great  diminution  in  the  number 
of  generic  types.  Many  of  the  old  genera,  which  flourished 
so  abundantly  in  Lower  Silurian  seas,  have  now  died  out; 
and  the  group  is  represented  chiefly  by  species  of  Cheirurus, 
Encrinurus,  Hordes,  Proetus,  Lichas,  Acidaspis,  Illanus,  Caly- 
mene{  Homalonotus,  ?.nd  Phacops — the  last  of  these,  one  of  the 
highest  and  most  beautiful  of  the  groups  of  Trilobites,  attaining 
here  its  maximum  of  development.  In  the  annexed  illustra- 
tion (fig.  64)  some  of  the  characteristic  Upper  Silurian  Trilo- 
bites are  represented — all,  however,  belonging  to  genera  which 
have  their  commencement  in  the  Lower  Silurian  period.  In 


Fig.  64. — Upper  Silurian  Trilobites.  a,  Cheirurus  bimucronatus,  Wenlock  and 
Caradoc ;  6,  Phacops  longicaudatus,  Wenlock,  Britain  and  America  ;  c,  Phacopt 
Downinglce,  Wenlock  and  Ludlow  ;  d,  Harpea  ungula,  Upper  Silurian,  Bohemia. 
(After  Salter  and  Barrande.) 

addition  to  the  above,  the  Ludlow  rocks  of  Britain  and  the 
Lower  Helderberg  beds  of  North  America  have  yielded  the 
remains  of  certain  singular  Crustaceans  belonging  to  the 
extinct  order  of  the  Eurypterida.  Some  of  these  wonderful 
forms  are  not  remarkable  for  their  size ;  but  others,  such  as 
Pterygotus  Anglicus  (fig.  65),  attain  a  length  of  six  feet  or  more, 
and  may  fairly  be  considered  as  the  giants  of  their  class.  The 
Eurypterids  are  most  nearly  allied  to  the  existing  King-crabs 
(Lhnuli),  and  have  the  anterior  end  of  the  body  covered  with 
a  great  head-shield,  carrying  two  pairs  of  eyes,  the  one  simple 


THE  UPPER  SILURIAN  PERIOD. 


127 


and  the  other  compound.  The  feelers  are  converted  into 
pincers,  whilst  the  last  pair  of  limbs  have  their  bases  covered 
with  spiny  teeth  so  as  to  act  as  jaws,  and  are  flattened  and 
widened  out  towards  their  extremities  so  as  to  officiate  as 
swimming-paddles.  The  hinder  extremity  of  the  body  is  com- 
posed of  thirteen  rings,  which  have  no  legs  attached  to  them; 
and  the  last  segment  of  the  tail  is  either  a  flattened  plate  or  a 
narrow,  sword-shaped  spine.  Fragments  of  the  skeleton  are 
easily  recognized  by  the  peculiar  scale-like  markings  with 
which  the  surface  is  adorned,  and 
which  look  not  at  all  unlike  the 
scales  of  a  fish.  The  most  fa- 
mous locality  for  these  great  Crus- 
taceans is  Lesmahagow,  in  Lan- 
arkshire, where  many  different 
species  have  been  found.  The 
true  King-crabs  (Limuli}  of  exist- 
ing seas  also  appear  to  have  been 
represented  by  at  least  one  form 
(Neolimulus}  in  the  Upper  Silu- 
rian. 

Coming  to  the  Mollusca,  we 
note  the  occurrence  of  the  same 
great  groups  as  in  the  Lower 
Silurian.  Amongst  the  Sea- 
mosses  (Polysoa},  we  have  the 
ancient  Lace-corals  (Fenestella 
and  Retepora},  with  the  nearly- 
allied  Glauconome,  and  species  of 
Ptilodictya  (fig.  66)  ;  whilst  many 
forms  often  referred  here  may 
probably  have  to  be  transferred 

tn    the    Cnrak      incf    as    snmp    sn  Fis-    65>  ~  Pterygotus    Anglicv*, 

orais,    JUS  viewed  from  the  under  side,  reduced 

called    Corals    will    ultimately    be      in  size  and  restored,    c  c,  The  feelers 

(antennae),  terminating  in  nipping- 
removed  to  the  present  group.  claws;  oo,  Eyes  ;mm,  Three  pairs  of 
The      TCrarViirmnHs      rrmtirmpH       jointed  limbs,  with  pointed  extremi- 
ties ;    n  n,  Swimming-saddles,    the 

to     flourish     during     the     Upper      bases  of  which  are  spiny  and  act  as 
0.,  ....  jaws.     Upper  Silurian,  Lanarkshire, 

bilunan  period  in  immense  num-      (After  Henry  Woodward.) 

bers     and    under    a    greatly    in- 
creased    variety     of     forms.       The     three     prominent     Lower 
Silurian    genera    Orthis,    Strophomena,    and    Leptana    are    still 
well    represented,    though    they    have    lost    their    former    pre- 
eminence.     Amongst    the    numerous    types    which    have    now 


128 


HISTORICAL  PALAEONTOLOGY. 


come  upon  the  scene  for  the  first  time,  or  which  have  now  a 
special    development,    are    Spirifera    and    Pentamerus.      In    the 


Aa, 


Fig.  66. — Upper  Silurian  Polyzoa.  1,  Fan-shaped  frond  of  Ehinopora  verrucosa;  la, 
Portion  of  the  surface  of  the  same,  enlarged  ;  2  and  2a,  Phcenopora  ensifonnis,  of  the 
natural  size  and  enlarged  ;  3  and  3a,  Helopora  fragilis,  of  the  natural  size  and  en- 
larged ;  4  and  4«,  Ptilodictya  raripora,  of  the  natural  size  and  enlarged.  The  speci- 
mens are  all  from  the  Clinton  Formation  (May  Hill  Group)  of  Canada.  (Original.) 

first  of  these  (fig.  69,  b,  c),  one  of  the  valves  of  the  shell  (the 
dorsal)  is  furnished  in  its  interior  with  a  pair  of  great  calca- 
reous spires,  which  served  for  the  support  of  the  long  and 


Fig.  67. — Spirifera  hysterica.    The  right-hand  figure  shows  the  interior  of  the 
dorsal  valve,  with  the  calcareous  spires  for  the  support  of  the  arms. 

fringed  fleshy  processes  or  "  arms  "  which  were  attached  to  the 
sides  of  the  mouth.  *  In  the  genus  Pentamerus  (fig.  70)  the 
shell  is  curiously  subdivided  in  its  interior  by  calcareous 
plates.  The  Pentameri  commenced  their  existence  at  the  very 
close  of  the  Lower  Silurian  (Llandovery),  and  survived  to  the 


*  In  all  the  Lamp-shells  the  mouth  is  provided  with  two  long  fleshy 
organs,  which  carry  delicate  filaments  on  their  sides,  and  which  are 
usually  coiled  into  a  spiral.  These  organs  are  known  as  the  "  arms," 
and  it  is  from  their  presence  that  the  name  of  "  BracJiiopoda  "  is  derived 
(Gr.  brachion,  arm;  podes,  feet).  In  some  cases  the  arms  are  merely  coiled 
away  within  the  shell,  without  any  support;  but  in  other  cases  they  are 
carried  upon  a  more  or  less  elaborate  shelly  loop,  often  ^spoken  of  as  the 
"  carriage-spring  apparatus."  In  the  Sbirifers,  and  in  other  ancient 
genera,  this  apparatus  is  coiled  up  into  a  complicated  spiral  (fig.  67).  It 
is  these  "  arms,"  with  or  without  the  supporting  loops  or  spires,  which 
serve  as  one  of  the  special  characters  distinguishing  the  Brachiopods  from 
the  true  Bivalves  (Lamcllibranchiata). 


THE  UPPER  SILURIAN  PERIOD. 


129 


close  of  the  Upper   Silurian ;  but  they  are  specially  character- 
istic  of    the    May    Hill    and    Wenlock   groups,    both    in    Britain 


e 


Fig.  68. — Upper  Silurian  Brachiopods.  a  a',  Leptoccelia  plano-convexa,  Clinton 
Group,  America;  b  b',  Rhynchonella  neglecta,  Clinton  Group,  America;  e,  Bhynchonella 
cuneata,  Niagara  Group,  America,  and  Wenlock  Group,  Britain  ;  d  d',  Orthls  elegan- 
tula,  Llandeilo  to  Ludlow,  America  and  Europe  ;  e  ef,  Atrypa  fiemispherica,  Clinton 
Group,  America,  and  Llandovery  and  May  Hill  Groups,  Britain  ;  ff,  Atrypa  congesta, 
Clinton  Group.  America  ;  g  g',  Orthls  Davidsoni,  Clinton  Group,  America.  (After 
Hall,  Billings,  and  the  Author. ) 

and   in    other    regions.      One    species,    Pentamerus   galeatus,    is 
common     to     Sweden,     Britain,     and    America.       Amongst    the 


Fig.  69 — a,  a'  Meriitella  intermedia,  Niagara  Group,  America  ;  b,  Spirifera  Nlagar- 
enste,  Niagara  Group,  America  ;  c  c',  Spirifera  crispa,  May  Hill  to  Ludlow,  Britain, 
and  Niagara  Group,  America;  d,  Strophomena  (Slreptorhynchiis}  subplana,  Niagara 
Group,  America  ;  e,  Meristella  naviformis,  Niagara  Group,  America  ;  /,  Meristella 
cylindrica,  Niagara  Group,  America.  (After  Hall,  Billings,  and  the  Author.) 

remaining    Upper    Silurian    Brachiopods    are    the    extraordinary 
Trimerellids;   the   old   and   at   the   same   time   modern   Lingula, 
Discing,   and    Crania;    together    with    many    species    of   Atrypa 
9 


130 


HISTORICAL  PALEONTOLOGY. 


(fig.  68,  e),  Leptocoelia  (fig.  68,  a),  Rhynchonella  (fig.  68,  b,  c), 
Meristella  (fig.  69,  a,  e,  /),  Athyris,  Reizia,  Chonetes,  &c. 


Fig.  lO.—Pentamerus  Enightii,    Wenlock  and  Ludlow.    The  right-hand 
figure  shows  the  internal  partitions  of  the  shell. 

The  higher  groups  of  the  Mollusca  are  also  largely  repre- 
sented in  the  Upper  Silurian.  Apart  from  some  singular  types, 
such  as  the  huge  and  thick-shelled  Megalomi  of  the  American 


11 

im 


c 


Fig.  71. — Upper  Silurian  Bivalves,  A,  Cardiola  interrupta,  Wenlock  and  Ludlow  ; 
B,  Pterinea  subfalcata,  Wenlock ;  C,  Cardiola  flbrota,  Ludlow.  (After  Salter  and 
M'Coy.) 

Wenlock  formation,  the  Bivalves  (Lamellibranchiata}  present 
little  of  special  interest ;  for  though  sufficiently  numerous,  they 
are  rarely  well  preserved,  and  their  true  affinities  are  often  un- 
certain. Amongst  the  most  characteristic  genera  of  this  period 
may  be  mentioned  Cardiola  (fig.  71,  A  and  C)  and  Pterinea,  (fig. 

71,  B),  though  the  latter  survives  to  a  much  later  date.     The 
Univalves  (Gasteropoda)  are  very  numerous,  and  a  few  charac- 
teristic forms  are  here  figured    (fig.  72).     Of  these,  no  genus 
is   perhaps   more   characteristic   than   Euomphalus    (fig.    72,    b), 
with   its   flat   discoidal    shell,   coiled  up   into   an   oblique    spiral, 
and   deeply   hollowed   out   on    one   side ;    but   examples   of   this 
group  are  both  of  older  and  of  more  modern  date.     Another 
very  extensive  genus,  especially  in  America,  is  Platyceras   (fig. 

72,  a  and  /),  with  its  thin  fragile  shell — often  hardly  coiled  up 
at  all — its  minute  spire,  and  its  widely-expanded,  often  sinuated 
mouth.      The    British    Acroculia    should    probably    be    placed 


THE  UPPER  SILURIAN  PERIOD. 


131 


here,  and  the  group  has  with  reason  been   regarded  as  allied 
to    the    Violet-snails    (lanthina)    of    the    open    Atlantic.      The 


Fig.  72.— Upper  Silurian  Gasteropoda,  a,  Platycerax  ventricosum,  Lower  Hel- 
derberg, America  ;  6,  Euomphalus  discors,  Wenlock,  Britain  ;  c,  Holopella  obaoleta, 
Ludlow,  Britain ;  d,  Platyschisma  lielicites,  Upper  Ludlow,  Britain  ;  e,  ffolopelia 
gruc.il i nr,  Wenlock,  Britain  ;  /,  Platyceras  multisinuatum,  Lower  Helderberg, 
America  ;  g,  Holopea  subconica,  Lower  Helderberg,  America  ;  h,  h'  Platyostama 
Niagarense,  Niagara  Group,  America.  (After  Hall,  M'Coy,  and  Salter.) 

species  of  Platyostoma  (fig.  72,  h}  also  belong  to  the  same 
family ;  and  the  entire  group  is  continued  throughout  the 
Devonian  into  the  Carboniferous.  Amongst  other  well-known 
Upper  Silurian  Gasteropods  are  species  of  the  genera  Holopea 
(fig.  72,  g},  Holopella  (fig.  72,  <?),  Platyschisma  (fig.  72,  rf), 
Cyclonema,  Pleurotomaria,  Murchisonia,  Trochonema,  &c.  The 
oceanic  Univalves  (Heteropods)  are  rep- 
resented mainly  by  species  of  Bellero- 
phon;  and  the  Winged  Snails,  or  Ptero- 
pods,  can  still  boast  of  the  gigantic  Thecce 
and  Conularia,  which  characterize  yet 
older  deposits.  The  commonest  genus 
of  Pteropoda,  however,  is  Tentaculites  (fig. 
73),  which  clearly  belongs  here,  though 
it  has  commonly  been  regarded  as  the 
tube  of  an  Annelide.  The  shell  in  this 
group  is  a  conical  tube,  usually  adorned 

with     prominent     transverse     rings,     and         ri«-  '3-—  Tentacuiitea 

.  ,      ..  ornatug.    Upper  Silurian  of 

often   with   finer  transverse   or   longitudi-     Europe  and  North  America. 

nal  striae  as  well;  and  many  beds  of  the 

Upper  Silurian  exhibit  myriads  of  such  tubes .  scattered  promis- 
cuously over  their  surfaces. 


132 


HISTORICAL  PALAEONTOLOGY. 


The  last  and  highest  group  of  the  Mollusca — that  of  the 
Cephalopoda  —  is  still  represented  only  by  Tetr abranchiate 
forms;  but  the  abundance  and  variety  of  these  is  almost 
beyond  belief.  Many  hundreds  of  different  species  are  known, 
chiefly  belonging  to  the  straight  Orthoceratites,  but  the  slightly- 
curved  Cyrtoceras  is  only  little  less  common.  There  are  also 
numerous  forms  of  the  genera  Phragmoceras,  Ascoceras,  Gyro- 
ceras,  Lituites,  and  Nautilus.  Here,  also,  are  the  first-known 
species  of  the  genus  Goniatites — a  group  which  attains  con- 
siderable importance  in  later  deposits,  and  which  is  to  be 
regarded  as  the  precursor  of  the  Ammonites  of  the  Secondary 
period. 

Finally,  we  find  ourselves  for  the  first  time  called  upon  to 
consider  the   remains   of   undoubted  vertebrate   animals,   in   the 
form  of  Fishes.     The   oldest   of   these   remains,   so   far   as  yet 
known,  are  found  in  the  Lower  Ludlow  rocks,  and  they  con- 
sist  of   the   bony   head-shields   or   bucklers 
of  certain  singular  armored  fishes  belong- 
ing  to    the   group    of    the    Ganoids,   repre- 
sented   at    the    present    day    by    the    Stur- 
geons,   the    Gar-pikes    of    North    America, 
and  a  few  other  less  familar  forms.     The 
principal  Upper  Silurian  genus  of  these  is 
Pterasf>is,and  the  annexed  illustration  (fig. 
74)    will  give  some  idea  of  the  extraordi- 
nary form  of  the  shield  covering  the  head 
in    these    ancient    fishes.      The    remarkable 

Fig.  74.-Head-shield  of  stratum  near  the  top   of  the   Ludlow   for- 
Pterospis  Banks  li,  Ludlow 
rocks.    (After  Murchison.)  mation    known     as     the       bone-bed       has 

also    yielded    the     remains     of     shark-like 
fishes.     Some  of  these,  for  which  the  name 

of    Onchus    has    been    proposed,    are    in    the    form    of    com- 
pressed, slightly-curved  spines   (fig.  75,  A),  which  would  appear 


Fig.  75. — A,  Spine  of  Onchus  tenuistriatua  ;  B,  Shagreen-scales  of  Thelodus.     Both 
from  the  "  bone-bed  "  of  the  Upper  Ludlow  rocks.     (After  Murchison. ) 

to  be  of  the  nature  of  the  strong  defensive  spines  implanted 
in  front  of  certain  of  the  fins  in  many  living  fishes.  Besides 
these,  have  been  found  fragments  of  prickly  skin  or  shagreen 
(SpJiagodus},  along  with  minute  cushion-shaped  bodies  (Thelo- 


THE  UPPER  SILURIAN  PERIOD.  133 

dus,  fig.  75,  B),  which  are  doubtless  the  bony  scales  of  some 
fish  resembling  the  modern  Dog-fishes.  As  the  above  mentioned 
remains  belong  to  two  distinct,  and  at  the  same  time  highly- 
organized,  groups  of  the  fishes,  it  is  hardly  likely  that  we  are 
really  presented  here  with  the  first  examples  of  this  great  class. 
On  the  contrary,  whether  the  so-called  "  Conodonts "  should 
prove  to  be  the  teeth  of  fishes  or  not,  we  are  justified  in  ex- 
pecting that  unequivocal  remains  of  this  group  of  animals  will 
still  be  found  in  the  Lower  Silurian.  It  is  interesting,  also,  to 
note  that  the  first  appearance  of  fishes — the  lowest  class  of 
vertebrate  animals — so  far  as  known  to  us  at  present,  does  not 
take  place  until  after  all  the  great  sub-kingdoms  of  invertebrates 
have  been  long  in  existence ;  and  there  is  no  reason  for  think- 
ing that  future  discoveries  will  materially  affect  the  relative 
order  of  succession  thus  indicated. 

LITERATURE. 

From  the  vast  and  daily-increasing  mass  of  Silurian  literature, 
it  is  impossible  to  do  more  than  select  a  small  number  of  works 
which  have  a  classical  and  historical  interest  to  the  English- 
speaking  geologists,  or  which  embody  researches  on  special 
groups  of  Silurian  animals — anything  like  an  enumeration  of  all 
the  works  and  papers  on  this  subject  being  wholly  out  of  the 
question.  Apart,  therefore,  from  numerous  and  in  many  cases 
extremely  important  memoirs,  by  various  well-known  observers, 
both  at  home  and  abroad,  the  following  are  some  of  the  more 
weighty  works  to  which  the  student  may  refer  in  investigating 
the  physical  characters  and  succession  of  the  Silurian  strata  and 
their  fossil  contents  : — 

(1)  'Siluria. '     Sir  Roderick  Murchison. 

(2)  '  Geology  of  Russia  and  Europe. '     Murchison   (with  M. 

de  Verneuil  and  Count  von  Keyserling). 

(3)  '  Bassin  Siluren  de  Boheme  Centrale. '  Barrande. 

(4)  '  Introduction  to  the  Catalogue  of  British  Palaeozoic  Fos- 

sils   in    the    Woodwardian     Museum    of     Cambridge. ' 
Sedgwick. 

(5)  '  Die  Urwelt  Russlands. '     Eichwald. 

(6)  '  Report   on  the   Geology  of   Londonderry,   Tyrone, '   &c. 

Portlock. 

(/)    "Geology    of    North    Wales "--'  Mem.    Geol.    Survey    of 
Great  Britain, '  vol.  iii.     Ramsay. 

(8)  'Geology  of  Canada.'  1863,  Sir  W.  E.  Logan;  and  the 

'  Reports   of    Progress   of   the   Geological    Survey '   since 
1863. 

(9)  '  Memoirs  of  the  Geological  Survey  of  Great  Britain. ' 
(10)  Reports  of  the  Geological  Surveys  of  the  State  of  New 

York,    Illinois,    Ohio,    Iowa,    Michigan,    Vermont,    Wis- 
consin,   Minnesota, '   &c.     By   Emmons,    Hall,    Worthen, 
Meek,  Newberry,  Orton,  Winchell,  Dale  Owen,  &c. 
(n)  *  Thesaurus  Siluricus. '     Bigsby. 


134  HISTORICAL  PALAEONTOLOGY. 

(12)  '  British  Palaeozoic  Fossils. '  M'Coy. 

(13)  'Synopsis  of  the  Silurian  Fossils  of  Ireland.'     M'Coy 

(14)  "Appendix   to   the    Geology   of    North    Wales  "--'Mem 

Geol.  Survey,'  vol.  iii.     Salter. 

(15)  'Catalogue  of  the  Cambrian  and  Silurian  Fossils  in  the 

Woodwardian   Museum   of  Cambridge. '     Salter. 

(16)  'Characteristic  British  Fossils.'     Baily. 

(17)  'Catalogue  of  British  Fossils.'     Morris. 

(18)  'Palaeozoic  Fossils  of  Canada.'     Billings. 

(19)  'Decades  of  the  Geological  Survey  of  Canada.'    Billings, 

Salter,  Rupert  Jones. 

(20)  '  Decades   of   the   Geological    Survey  of   Great   Britain. ' 

Salter,  Edward  Forbes. 

(21)  'Palaeontology  of  New  York,'  vols  i.-iii.     Hall. 

(22)  '  Palaeontology  of  Illinois. '     Meek  and  Worthen. 

(23)  'Palaeontology  of  Ohio.'     Meek,  Hall,  Whitfield,  Nichol- 

son. 

(24)  'Silurian  Fauna  of  West  Tennessee'   (Silurische  Fauna 

des  Westlichen  Tennessee).     Ferdinand  Roemer. 

(25)  '  Reports  on  the  State  Cabinet  of  New  York. '     Hall. 

(26)  '  Lethaea  Geognostica. '     Bronn. 

(27)  '  Index  Palaeontologicus. '  Bronn. 

(28)  '  Lethaea  Rossica. '  Eichwald. 

(29)  '  Lethaea  Suecica. '     Hisinger. 

(30)  '  Palaeontologica  Suecica. '     Angelin. 

(31)  '  Petref  acta  Germaniae. '     Goldfuss. 

(32)  '  Versteinerungen  der  Grauwacken-Formation  in  Sachsen. ' 

Geinitz. 

(33)  'Organization  of  Trilobites '  (Ray  Society).    Burmeister. 

(34)  'Monograph  of  the  British  Trilobites'   (Palaeontograph- 

ical  Society).     Salter. 

(35)  'Monograph    of    the    British    Merostomata'    (Palaeonto- 

graphical  Society).     Henry  Woodward. 

(36)  'Monograph  of  British  Brachiopoda'   ( Palaeontolograph- 

ical  Society).    Thomas  Davidson. 

(37)  '  Graptolites  of  the  Quebec  Group. '     James  Hall. 

(38)  '  Monograph  of  the  British  Graptolitidae. '     Nicholson. 

(39)  '  Monographs  on  the  Trilobites,  Pteropods,  Cephalopods, 

Graptolites, '  &c.    Extracted  from  the  '  Systeme  Silurien 
du  Centre  de  la  Boheme. '    Barrande. 

(40)  '  Polypiers    Fossiles    des    Terrains    Paleozoiques. '    and 

'Monograph  of  the  British  Corals'   (  Palaeontographical 
Society).    Milne  Edwards  and  Jules  Haime. 


CHAPTER  XL 

THE  DEVONIAN  AND  OLD  RED  SANDSTONE 

PERIOD. 

Between  the  summit  of  the  Ludlow  formation  and  the  strata 
which  are  universally  admitted  to  belong  to  the  Carboniferous 
series  is  a  great  system  of  deposits,  to  which  the  name  of  "  Old 


DEVONIAN  AND  OLD  RED  PERIOD.  135 

Red  Sandstone"  was  originally  applied,  to  distinguish  them 
from  certain  arenaceous  strata  which  lie  above  the  coal  ("  New 
Red  Sandstone").  The  Old  Red  Sandstone,  properly  so- 
called,  was  originally  described  and  investigated  as  occurring 
in  Scotland  and  in  South  Wales  and  its  borders;  and  similar 
strata  occur  in  the  south  of  Ireland.  Subsequently  it  was 
discovered  that  Sediments  of  a  different  mineral  nature,  and 
containing  different  organic  remains,  intervened  between  the 
Silurian  and  the  Carboniferous  rocks  on  the  continent  of  Eu- 
rope, and  strata  with  similar  palseontological  characters  to  these 
were  found  occupying  a  considerable  area  in  Devonshire.  The 
name  of  "  Devonian "  was  applied  to  these  deposits ;  and  this 
title,  by  common  usage,  has  come  to  be  regarded  as  synony- 
mous with  the  name  of  "  Old  Red  Sandstone. "  Lastly,  a 
magnificent  series  of  deposits,  containing  marine  fossils,  and 
undoubtedly  equivalent  to  the  true  "Devonian"  of  Devon- 
shire, Rhenish  Prussia,  Belgium,  and  France,  is  found  to  inter- 
vene in  North  America  between  the  summit  of  the  Silurian 
and  the  base  of  the  Carboniferous  rocks. 

Much  difficulty  has  been  felt  in  correlating  the  true  "  Devon- 
ian Rocks  "  with  the  typical  "  Old  Red  Sandstone  "—  this  diffi- 
culty arising  from  the  fact  that  though  both  formations  are 
fossiliferous,  the  peculiar  fossils  of  each  have  only  been  rarely 
and  partially  found  associated  together.  The  characteristic 
crustaceans  and  many  of  the  characteristic  fishes  of  the  Old 
Red  are  wanting  in  the  Devonian ;  whilst  the  corals  and 
marine  shells  of  the  latter  do  not  occur  in  the  former.  It  is 
impossible  here  to  enter  into  any  discussion  as  to  the  merits 
of  the  controversy  to  which  this  difficulty  has  given  origin. 
No  one,  however,  can  doubt  the  importance  and  reality  of  the 
Devonian  series  as  an  independent  system  of  rocks  to  be  in- 
tercalated in  point  of  time  between  the  Silurian  and  the  Car- 
boniferous. The  want  of  agreement,  both  lithologically  and 
palaeontologically,  between  the  Devonian  and  the  Old  Red, 
can  be  explained  by  supposing  that  these  two  formations, 
though  wholly  or  in  great  part  contemporaneous,  and  therefore 
strict  equivalents,  represent  deposits  in  two  different  geograph- 
ical areas,  laid  down  under  different  conditions.  On  this  view, 
the  typical  Devonian  rocks  of  Europe,  Britain,  and  North 
America  are  the  deep-sea  deposits  of  the  Devonian  period,  or, 
at  any  rate,  are  genuine  marine  sediments  formed  far  from 
land.  On  the  other  hand,  the  "Old  Red  Sandstone"  of' 
Britain  and  the  corresponding  "  Gaspe  Group "  of  Eastern 


136  HISTORICAL  PALAEONTOLOGY. 

Canada  represent  the  shallow-water  shore-deposits  of  the  same 
period.  In  fact,  the  former  of  these  last-mentioned  de- 
posits contains  no  fossils  which  can  be  asserted  positively 
to  be  marine  (unless  the  Eurypterids  be  considered  so)  ;  and 
it  is  even  conceivable  that  it  represents  the  sediments  of  an 
inland  sea.  Accepting  this  explanation  in  the  meanwhile, 
we  may  very  briefly  consider  the  general  succession  of  the 
deposits  of  this  period  in  Scotland,  in  Devonshire,  and  in 
North  America. 

In  Scotland  the  "  Old  Red "  forms  a  great  series  of  arena- 
ceous and  conglomeratic  strata,  attaining  a  thickness  of  many 
thousands  of  feet,  and  divisible  into  three  groups.  Of  these, 
the  Loiver  Old  Red  Sandstone  repose  with  perfect  conform- 
ity upon  the  highest  beds  of  the  Upper  Silurian,  the  two  for- 
mations being  almost  inseparably  united  by  an  intermediate 
series  of  "  passage-beds. "  In  mineral  nature  this  group  con- 
sists principally  of  massive  conglomerates,  sandstones,  shales, 
and  concretionary  limestones;  and  its  fossils  consist  chiefly  of 
large  crustaceans  belonging  to  the  family  of  the  Eurypterids, 
fishes,  and  plants.  The  Middle  Old  Red  Sandstone  consists  of 
flagstones,  bituminous  shales,  and  conglomerates,  sometimes 
with  irregular  calcareous  bands;  and  its  fossils  are  principally 
fishes  and  plants.  It  may  be  wholly  wanting,  when  the  Upper 
Old  Red  seems  to  repose  unconformably  upon  the  lower  divi- 
sion of  the  series.  The  Upper  Old  Red  Sandstone  consists  of 
conglomerates  and  grits,  along  with  a  great  series  of  red  and 
yellow  sandstones — the  fossils,  as  before,  being  fishes  and  re- 
mains of  plants.  The  Upper  Old  Red  graduates  upwards 
conformably  into  the  Carboniferous  series. 

The  Devonian  rocks  of  Devonshire  are  likewise  divisible 
into  a  lower,  middle,  and  upper  division.  The  Lower 
Devonian  or  Lynton  Group  consists  of  red  and  purple  sand- 
stones, with  marine  fossils,  corresponding  to  the  "  Spirifer 
Sandstein "  of  Germany,  and  to  the  arenaceous  deposits  (Scho- 
harie  and  Cauda-Galli  Grits)  at  the  base  of  the  American 
Devonian.  The  Middle  Devonian  or  Ilfracombe  Group  consists 
of  sandstones  and  flags,  with  calcareous  slates  and  crystalline 
limestones,  containing  many  corals.  It  corresponds  with  the 
great  "  Eif  el  Limestone "  of  the  Continent,  and,  in  a  general 
way,  with  the  Corniferous  Limestone  and  Hamilton  Group  of 
North  America.  The  Upper  Devonian  or  Pilton  Group,  lastly, 
consists  of  sandstones  and  calcareous  shales  which  correspond 
with  the  "  Clymenia  Limestone "  and  Cyprindina  Shales "  of 


DEVONIAN  AND  OLD  RED  PERIOD.  137 

the  Continent,  and  with  the  Chemung  and  Portage  groups  of 
North  America.  It  seems  quite  possible,  also,  that  the  so- 
called  "  Carboniferous  Slates "  of  Ireland  correspond  with 
this  group,  and  that  the  former  would  be  more  properly  re- 
garded as  forming  the  summit  of  the  Devonian  than  the 
base  of  the  Carboniferous. 

In  no  country  m  the  world,  probably,  is  there  a  finer 
or  more  complete  exposition  of  the  strata  intervening  be- 
tween the  Silurian  and  Carboniferous  deposits  than  in  the 
United  States.  The  following  are  the  main  subdivisions 
of  the  Devonian  rocks  in  the  State  of  New  York,  where 
the  series  may  be  regarded  as  being  typically  developed 
(%  67)  :- 

(1)  Cauda-Galli  Grit  and  Schoharie  Grit. — Considering  the 
"  Oriskany   Sandstone "   as   the   summit  of   the   Upper    Silurian, 
the    base    of    the    Devonian    is    constituted    by    the    arenaceous 
deposits  known  by  the  above  names,  which  rest  quite  conform- 
ably    upon     the     Silurian,     and     which     represent     the     Lower 
Devonian    of    Devonshire.      The    Cauda-Galli    Grit    is    so-called 
from    the    abundance    of    a    peculiar    spiral    fossil    (Spirophyton 
cauda-Galli),   which   is   of   common   occurrence   in   the    Carbon- 
iferous  rocks   of   Britain,   and   is    supposed   to   be   the    remains 
of  a  sea-weed. 

(2)  The   Corniferous  or   Upper  Helderberg   Limestone. — A 
series    of    limestones    usually    charged    with    considerable    quan- 
tities  of   siliceous   matter   in   the    shape   of   hornstone    or   chert 
(Lat.  cornu,  horn).     The  thickness  of  this  group  rarely  exceeds 
3000   feet ;   but   it   is   replete   with    fossils,    more    especially   with 
the    remains    of    corals.      The    Corniferous    Limestone    is    the 
equivalent   of   the   coral-bearing   limestones    of   the    Middle   De- 
vonian   of    Devonshire    and    the    great    "  Eif  el    Limestone "    of 
Germany. 

(3)  The  Hamilton  Group — consisting  of  shales  at  the  base 
("  Marcellus    shales ")  ;    flags,    shales,    and    impure    limestones 
("Hamilton  beds")  in  the  middle;  and  again  a  series  of  shales 
("Genesee   Slates")    at  the  top.     The  thickness   of  this  group 
varies    from    200   to    1200    feet,    and    it    is    richly   charged    with 
marine  fossils. 

(4)  The  Portage  Group. — A  great  series  of  shales,  flags  and 
shaly  sandstones,  with  few  fossils. 

(5)  The   Chemung   Group. — Another  great   series   of   sand- 
stones  and    shales,   but   with    many    fossils.     The    Portage   and 
Chemung  groups  may  be   regarded  as  corresponding  with   the 


138  HISTORICAL  PALEONTOLOGY. 

Upper  Devonian  of  Devonshire.  The  Chemung  beds  are 
succeeded  by  a  great  series  of  red  sandstones  and  shales — the 
"  Catskill  Group " — which  pass  conformably  upwards  into  the 
Carboniferous,  and  which  may  perhaps  be  regarded  as  the 
equivalent  of  the  great  sandstones  of  the  Upper  Old  Red  in 
Scotland. 

Throughout  the  entire  series  of  Devonian  deposits  in  North 
America  no  unconformability  or  physical  break  of  any  kind 
has  hitherto  been  detected;  nor  is  there  any  marked  interrup- 
tion to  the  current  of  life,  though  each  subdivision  of  the  series 
has  its  own  fossils.  No  completely  natural  line  can  thus  be 
indicated,  dividing  the  Devonian  in  this  region  from  the  Silu- 
rian on  the  one  hand,  and  the  Carboniferous  on  the  other 
hand.  At  the  same  time,  there  is  the  most  ample  evidence, 
both  stratigraphical  and  palaeontological,  as  to  the  complete 
independence  of  the  American  Devonian  series  as  a  distinct 
life-system  between  the  older  Silurian  and  the  later  Carbon- 
iferous. The  subjoined  section  (fig.  76)  shows  diagrammatic- 
ally  the  general  succession  of  the  Devonian  rocks  of  North 
America. 

As  regards  the  life  of  the  Devonian  period,  we  are  now 
acquainted  with  a  large  and  abundant  terrestrial  flora — this 
being  the  first  time  that  we  have  met  with  a  land  vegetation 
capable  of  reconstruction  in  any  fulness.  By  the  researches 
of  Cceppert,  Unger,  Dawson,  Carruthers,  and  other  botanists, 
a  knowledge  has  been  acquired  of  a  large  number  of  Devonian 
plants,  only  a  few  of  which  can  be  noticed  here.  As  might 
have  been  anticipated,  the  greater  number  of  the  vegetable 
remains  of  this  period  have  been  obtained  from  such  shallow- 
water  deposits  as  the  Old  Red  Sandstone  proper  and  the  Gaspe 
series  of  North  America,  and  few  traces  of  plant-life  occur  in 
the  strictly  marine  sediments.  Apart  from  numerous  remains, 
mostly  of  a  problematical  nature,  referred  to  the  comprehensive 
group  of  the  Sea-weeds,  a  large  number  of  Ferns  have  now 
been  recognized,  some  being  of  the  ordinary  plant-like  type 
(Pecopteris,  Neuropteris',  Alethopteris,  Sphenopteris,  &c.),  whilst 
others  belong  to  the  gigantic  group  •  of  the  "  Tree-ferns " 
(Psaronius,  Canlopteris,  &c.)  Besides  these  there  is  an  abun- 
dant development  of  the  singular  extinct  types  of  the  Lepido- 
dendroids,  the  Sigillarioids,  and  the  Calamites,  all  of  which 
attained  their  maximum  in  the  Carboniferous.  Of  these,  the 
Lepidodendra  may  be  regarded  as  gigantic,  tree-like  Club-mosses 


DEVONIAN  AND  OLD  RED  PERIOD. 


139 


GENERALIZED  SECTION  OF  THE  DEVONIAN  ROCKS  OF 
NORTH  AMERICA. 

Fig.  76. 


Catskill  Group. 

Chemung  Group. 
Portage  Group. 

Hamilton  Group. 

Corniferous  Limestone. 

Schoharie  Grit. 
Cauda-Galli  Grit. 
Oriskany   Sandstone. 

Lower  Helderberg. 


;  the  Calamites  are  equally  gigantic  Horse-tails 
(Equisetacea}  ;  and  the  Sigillarioids,  equally  huge  in  size,  in 
some  respects  hold  a  position  intermediate  between  the  Club- 
mosses  and  the  Pines  (Conifers^.  The  Devonian  rocks  have 
also  yielded  traces  of  many  other  plants  (such  as  Annularia, 
Asteropliyllites,  Cardiocarpon,  &c.),  which  acquire  a  greater  pre- 
dominance in  the  Carboniferous  period,  and  which  will  be 
spoken  of  in  discussing  the  structure  of  the  plants  of  the  Coal- 
measures.  Upon  the  whole,  the  one  plant  which  may  be  con- 
sidered as  specially  characteristic  of  the  Devonian  (though  not 
confined  to  this  series)  is  the  Psilophyton  (fig.  77)  of  Dr.  Daw- 
son.  These  singular  plants  have  slender  branching  stems, 
with  sparse  needle-shaped  leaves,  the  young  stems  being  at 


140 


HISTORICAL   PALEONTOLOGY. 


first  coiled  up,  crosier-fashion,  like  the  young  fronds  of  ferns, 
whilst  the  old  branches  carry  numerous  spore-cases.  The 
stems  and  branches  seem  to  have  attained  a  height  of  two  or 
three  feet ;  and  they  sprang  from  prostrate  "  root-stocks "  or 

creeping  stems.  Upon  the  whole, 
Principal  Dawson  is  disposed  to 
regard  Psilophyton  as  a  "  general- 
ized type"  of  plants  intermediate 
between  the  Ferns  and  the  Club- 
mosses.  Lastly,  the  Devonian  de- 
posits have  yielded  the  remains  of 
the  first  actual  trees  with  which  we- 
are  as  yet  acquainted.  About  the 
nature  of  some  of  these  (Ormoxy- 
lon  and  Dadoxylon}  no  doubt  can 
be  entertained, "since  their  trunks 
not  only  show  the  concentric  rings 
of  growth  characteristic  of  exog- 
enous trees  in  general,  but  their 
woody  tissue  exhibits  under  the 
microscope  the  "  discs  "  which  are 
characteristic  of  the  wood  of  the 
Pines  and  Firs  (see  fig.  2).  The 
singular  genus  Prototaxites,  how- 
ever, which  occurs  in  an  older  por- 
tion of  the  Devonian  series  than 
the  above,  is  not  in  an  absolutely 
unchallenged  position.  By  Prin- 
cipal Dawson  it  is  regarded  as  the 
trunk  of  an  ancient  Conifer — the 
most  ancient  known ;  but  Mr. 
Carruthers  regards  it  as  more 
probably  the  stem  of  a  gigantic 
sea-weed.  The  trunks  of  Proto- 
taxites (fig.  78,  A)  vary  from  one 
to  three  feet  in  diameter,  and 
exhibit  concentric  rings  of  growth  ; 
but  its  woody  fibres  have  not 
hitherto  been  clearly  demonstrated 
to  possess  discs.  Before  leaving 

the  Devonian  vegetation,  it  may  be  mentioned  that  the  hornstone 
or  chert  so  abundant  in  the  Corniferous  limestone  of  North 
America  has  been  shown  to  contain  the  remains  of  various 


Fig.  11.  —  Restoration  of  Psilo- 
phyton princeps  Devonian,  Can- 
ada. (After  Dawson.) 


DEVONIAN  AND  OLD  RED  PERIOD. 


141 


microscopic  plants  (Diatoms  and  Desmids).  We  find  also  in 
the  same  siliceous  material  the  singular  spherical  bodies,  with 
radiating  spines,  which  occur  so  abundantly  in  the  chalk  flints, 
and  which  are  termed  Xanthidia.  These  may  be  regarded 
as  probably  the  spore-cases  of  the  minute  plants  known  as 
Desmidice. 


Fig.  78. — A,  Trunk  of  Prototaxites  Logam,  eighteen  inches  in  diameter,  as  seen  in 
the  cliff  near  L'Anse  Brehaut,  Gasp6  ;  B,  Two  wood-cells  showing  spiral  fibres  and 
obscure  pores,  highly  magnified.  Lower  Devonian,  Canada.  (After  Dawson. ) 

The  Devonian  Protozoans  have  still  to  be  fully  investi- 
gated. True  Sponges  (such  as  Astrceospongia,  Sphcerospongia, 
&c.)  are  not  unknown;  but  by  far  the  commonest  repre- 
sentatives of  this  sub-kingdom  in  the  Devonian  strata  are 
Stromatopora  and  its  allies.  These  singular  organisms  (fig. 
79)  are  not  only  very  abundant  in  some  of  the  Devonian  lime- 
stones— both  in  the  Old  World  and  the  New — but  they  often 
attain  very  large  dimensions.  However  much  they  may  differ 
in  minor  details,  the  general  structure  of  these  bodies  is  that 
of  numerous,  concentrically-arranged,  thin,  calcareous  laminae, 
separated  by  narrow  interspaces,  which  in  turn  are  crossed  by 
numerous  delicate  vertical  pillars,  giving  the  whole  mass  a 
cellular  structure,  and  dividing  it  into  innumerable  minute 
quadrangular  compartments.  Many  of  the  Devonian  Stromato- 


142 


HISTORICAL  PALEONTOLOGY. 


pores  also  exhibit  on  their  surface  the  rounded  openings  of 
canals,  which  can  hardly  have  served  any  other  purpose  than 
that  of  permitting  the  sea-water  to  gain  ready  access  to  every 
part  of  the  organism. 

No  true  Graptolites  have  ever  been  detected  in  strata  of 
Devonian  age;  and  the  whole  of  this  group  has  become  ex- 
tinguished---unless  we  refer  here  the  still  surviving  Dictyonema. 
The  Ccclenterates,  however,  are  represented  by  a  vast  number 
of  Corals,  of  beautiful  forms  and  very  varied  types.  The 
marbles  of  Devonshire,  the  Devonian  limestones  of  the  Eifel 


Fig  79 .  — a,  Part  of  the  under  surface  of  Stromatopora  tuberculata,  showing  the 
wrinkled  basement  membrane  and  the  openings  of  water-canals,  of  the  natural  size  ; 
6,  Portion  of  the  upper  surf  ace  of  the  same,  enlarged;  c,  Vertical  section  of  a  fragment, 
magnified  to  show  the  internal  structure.  Corniferous  Limestone,  Canada.  (Original.) 

and  of  France,  and  the  calcareous  strata  of  the  Corniferous 
and  Hamilton  groups  of  America,  are  often  replete  with  the 
skeletons  of  these  organisms — so  much  so  as  to  sometimes 
entitle  the  rock  to  be  considered  as  representing  an  ancient 
coral-reef.  In  some  instances  the  Corals  have  preserved  their 
primitive  calcareous  composition;  and  if  they  are  embedded 
in  soft  shales,  they  may  weather  out  of  the  rock  in  almost  all 
their  original  perfection.  In  other  cases,  as  in  the  marbles  of 
Devonshire,  the  matrix  is  so  compact  and  crystalline  that  the 


DEVONIAN  AND  OLD  RED  PERIOD. 


143 


included  corals  can  only  be  satisfactorily  studied  by  means  of 
polished  sections.  In  other  cases,  again,  the  corals  have  been 
more  or  less  completely  converted  into  flint,  as  in  the  Cornifer- 


Fig.  81 .—  Zaphrentia  cornicula,  of  the 
natural  size.  Devonian,  America.  (Orig- 
inal.) 


Fig.  80.  —  Ci/stipfii/lluin  vesiculosum, 
showing  a  succession  of  cups  produced  by 
budding  from  the  original  coral.  Of  the 
natural  size.  Devonian,  America  and 
Europe.  (Original.) 


F\g.82.—ffeliophyllum  exiffuum,  view- 
ed from  in  front  and  behind.  Of  the  nat- 
ural size. Devonian.Canada.  (Original.) 


ous  limestone  of  North  America.  When  this  is  the  case,  they 
often  come,  by  the  action  of  the  weather,  to  stand  out  from 
the  enclosing  rock  in  the  boldest  relief,  exhibiting  to  the  ob- 


144  HISTORICAL  PALEONTOLOGY. 

server  the  most  minute  details  of  their  organization.  As  before, 
the  principal  representatives  of  the  Corals  are  still  referable  to 
the  groups  of  the  Rugosa  and  Tabulata.  Amongst  the  Rugose 
group  we  find  a  vast  number  of  simple  "  cup-corals, "  generally 
known  by  the  quarrymen  as  "  horns, "  from  their  shape.  Of 
the  many  forms  of  these,  the  species  of  Cyathophyllum,  Helio- 
phyllum  (fig.82~),Zaphrentis  (fig.  81),  and  Cystiphyllum  (fig.  80), 
are  perhaps  those  most  abundantly  represented — none  of  these 
genera,  however,  except  Heliophyllum,  being  peculiar  to  the 


Fig.  83.— Portion  of  a  mass  of  Crepidophyllum  Archiaci,  of  the  natural  size. 
Hamilton  Formation,  Canada.    (After  Billings.) 

Devonian  period.  There  are  also  numerous  compound  Ru- 
gose corals,  such  as  species  of  Eridophyllum,  Diphyphyl- 
lum,  Syringopora,  Phillip sastrcea,  and  some  of  the  forms  of 
Cyathophyllum  and  Crepidophyllum  (fig.  83).  Some  of  these 
compound  corals  attain  a  very  large  size,  and  form  of  them- 
selves regular  beds,  which  have  an  analogy,  at  any  rate,  with 
existing  coral-reefs,  though  there  are  grounds  for  believing  that 
these  ancient  types  differed  from  the  modern  reef-builders  in 
being  inhabitants  of  deep  water.  The  "  Tabulate  Corals "  are 
hardly  less  abundant  in  the  Devonian  rocks  than  the  Rugosa; 
and  being  invariably  compound,  they  hardly  yield  to  the  latter 
in  the  dimensions  of  the  aggregations  which  they  sometimes 
form. 

The  commonest,  and  at  the  same  time  the  largest,  of  these 
are  the  "  honeycomb  corals, "  forming  the  genus  Favosites 
(figs.  84,  85),  which  derive  both  their  vernacular  and  their 
technical  names  from  their  great  likeness  to  masses  of  petrified 


DEVONIAN  AND  OLD  RED  PERIOD. 


145 


honeycomb.  The  most  abundant  species  are  Favosites  Goth- 
landica  and  F.  hemispherica,  both  here  figured,  which  form 
masses  sometimes  not  less  than  two  or  three  feet  in  diameter. 
Whilst  Favosites  has  acquired  a  popular  name  by  its  honey- 
combed appearance,  the  resemblance  of  Michelinia  to  a  fossil- 
ized wasp's  nest  with  the  comb  exposed  is  hardly  less  strik- 
ing, and  has  earned  for  it  a  similar  recognition  from  the 


Fig.  84. — Portion  of  a  mass  of  Favo- 
titex  Gottilandtca,  of  the  natural  size. 
Upper  Silurian  and  Devonian  of  Europe 
and  America.  (Original.) 


Fig.  85.— Fragment  of  Favosites  fiemi- 
tpherica,  of  the  natural  size.  Upper  Silu- 
rian and  Devonian  of  America.  (After 
Billings.) 


non-scientific  public.  In  addition  to  these,  there  are  numer- 
ous branching  or  plant-like  Tabulate  Corals,  often  of  the  most 
graceful  form,  which  are  distinctive  of  the  Devonian  in  all 
parts  of  the  world. 

The  Echinodcnns  of  the  Devonian  period  call  for  little 
special  notice.  Many  of  the  Devonian  limestones  are  "  crin- 
oidal;"  and  the  Crinoids  are  the  most  abundant  and  widely- 
distributed  representatives  of  their  class  in  the  deposits  of 
this  period. 

The  Cystideans,  with  doubfful  exceptions,  have  not  been 
recognized  in  the  Devonian;  and  their  place  is  taken  by  the 
allied  group  of  the  "  Pentremites, "  which  will  be  further  spoken 
of  as  occurring  in  the  Carboniferous  rocks.  On  the  other  hand, 
the  Star-fishes,  Brittle-fishes,  and  Sea-urchins  are  all  continued 
by  types  more  or  less  closely  allied  to  those  of  the  preceding 
Upper  Silurian. 

Of  the  remains  of  Ringed-worms  (Annelidcs),  the  most 
numerous  and  the  most  interesting  are  the  calcareous  envelopes 
of  some  small  tube-inhabiting  species.  No  one  who  has  visited 
the  seaside  can  have  failed  to  notice  the  little  spiral  tubes  of 
the  existing  Spirorbis  growing  attached  to  shells,  or  covering 


146 


HISTORICAL  PALEONTOLOGY. 


Fig.  86.— a,  Spirorbia  omphalode»  natural  size 
and  enlarged,  Devonian,  Europe  and  America  ; 
b,  Spirorbis  Arkonensit,  of  the  natural  size  and 
enlarged  ;  c,  The  same,  with  the  tube  twisted  in 
the  reverse  direction.  Devonian,  America.  (Orig- 
inal.) 


the  fronds  of  the  commoner  Sea- weeds  (especially  Fucus  ser- 
ratus}.  These  tubes  are  inhabited  by  a  small  Annelide,  and 
structures  of  a  similar  character  occur  not  uncommonly  from 
the  Upper  Silurian  upwards.  In  the  Devonian  rocks,  Spir- 
orbis is  an  extremely  common  fossil,  growing  in  hundreds 
attached  to  the  outer  surface  of  corals  and  shells,  and  appearing 
in  many  specific  forms  (figs.  86  and  87)  ;  but  almost  all  the 
known  examples  are  of  small  size,  and  are  liable  to  escape  a 

cursory  examination. 

The  Crustaceans  of 
the  Devonian  are  prin- 
cipally Eurypterids  and 
Trilobites.  Some  of  the 
former  attain  gigantic 
dimensions,  and  the 
quarrymen  in  the  Scotch 
Old  Red  give  them  the 
name  of  "  seraphim, " 
from  their  singular 
scale  -  like  ornamenta- 
tion. The  Trilobites, 
though  still  sufficiently 
abundant  in  some  local- 
ities, have  undergone  a 
yet  further  diminution 

Fig.  87.— a  6,  Spirorbis  laxus,  enlarged,  Upper  since    tne    close    of    the 

Silurian,  America  ;  c,  Spirorbis  spinulifera,  of  the  Tinner  Silurian     Tn  both 

natural  size  and  enlarged,  Devonian,  Canada.   (Af-  ~PP  ^                ?'    1 

ter  Hall  and  the  Author. )  America     and     Europe 

quite  a  number  of  gen- 

sric  types  have  survived  from  the  Silurian,  but  few  or  no  new 
ones  make  their  appearance  during  this  period  in  either  the  Old 
World  or  the  New.  The  species,  however,  are  distinct;  and  the 
principal  forms  belong  to  the  genera  Phacops  (fig.  88,  a,  c,  d), 
Homalonotus  (fig.  88,  6),  Proetus,  and  Bronteus.  The  species 
figured  opposite  under  the  name  of  Phacops  latifrons  (fig.  88,  a), 
has  an  almost  world-wide  distribution,  being  found  in  the 
Devonian  of  Britain,  Belgium,  France,  Germany,  Russia,  Spain, 
and  South  America;  whilst  its  place  is  taken  in  North  Amer- 
ica by  the  closely-allied  Phacops  rana.  In  addition  to  the 
Trilobites,  the  Devonian  deposits  have  yielded  the  remains  of 
a  number  of  the  minute  Ostracoda,  such  as  Entomis  ("  Cypri- 
dina"),  Leperditia,  &c.,  which  sometimes  occur  in  vast  num- 
bers, as  in  the  so-called  "  Cypridina  Slates"  of  the  German 


DEVONIAN  AND  OLD  RED  PERIOD. 


147 


Devonian.  There  are  also  a  few  forms  of  Phyllopods  (Es- 
therid).  Taken  as  a  whole,  the  Crustacean  fauna  of  the 
Devonian  period  presents  many  alliances  with  that  of  the 


Fig.  88 — Devonian  Trilobites.  a,  Pfiacops  lalifrona,  Devonian  of  Britain,  the  Con- 
tinent of  Europe,  and  South  America  ;  6,  Homalonotua  armatits,  Europe  ;  c,  Phacop* 
(Trimerocepkalus)  Icevis,  Europe;  d,  Head-shield  of  Phacopt  (Portlockia)  granulatus, 
Europe.  (After  Salter  and  Bucmeister.) 

Upper   Silurian,  but  has  only  slight  relationships  with  that  of 
the  Lower  Carboniferous. 

Besides  Crustaceans,  we  meet  here  for  the  first  time  with 
the  remains  of  air-breathing  Articulates,  in  the  shape  of  Insects. 
So    far,    these    have    only    been    obtained    from    the    Devonian 
rocks  of  North  America,  and  they  indicate  the  existence  of  'at 
least  four  generic  types,  all  more  or  less  allied  to  the  existing 
May-flies    (Ephemerida).      One   of    these    interesting   primitive 
insects,  namely,  Platephemera  antiqua  (fig.  89),  appears  to  have 
measured  five  inches  in  ex- 
panse of  wing;  and  another 
(Xenoneura       antiquorum} 
has  attached  to  its  wing  the 
remains  of  a  "  stridulating- 
organ  "  similar  to  that  pos- 
sessed by  the  modern  Grass- 
hoppers— the  instrument,  as 
Principal  Dawson   remarks, 
of  "  the  first  music  of  living         rig.  89.— wing  of  piatephemera  anti- 
things  that  Geology  as  yet      ££,  Devonlan'  America«    (After  Daw' 
reveals  to  us.  " 

Amongst  the  Mollusca,  the  Devonian  rocks  have  yielded  a 


148 


HISTORICAL  PALAEONTOLOGY. 


great  number  of  the  remains  of  Sea-mosses   (Polysoa).     Some 
of  these  belong  to  the  ancient  type  Ptilodictya,  which  seems  tc 


Fig.  91.  — Fragment  of 
Ceriopora    Hamiltonensls, 
of    the  natural  size    and 
Fig.  90. — Fragment   of  Clathopora    intertexta,    of   the  enlarged.  Devonian,  Cana- 
natural  size  and  enlarged.   Devonian,  Canada.    (Original.)  da.    (Original.) 


disappear  here,  or  to  the  allied  Clathropora  (fig.  90),  with  its 
fenestrated  and  reticulated  fronds.  We  meet  also  with  the 
graceful  and  delicate  stems  of  Ceriopora  (fig.  91). 


Fig.  92. — Fragment  of  Fenestella  magnified, 
of  the  natural  size  and  enlarged.  Devonian, 
Canada.  (Original.) 


Fig.  93. — Fragment  of  Retepora 
Phillipai,  of,  the  natural  size  and 
enlarged.  Devonian,  Canada.  (Orig- 
inal.) 


Fig.  94.— Fragment  of  Fenettella 
cribrosa,  of  the  natural  size  and  en- 
larged. Devonian,Canada.  (Original.) 


The  majority  of  the  Devonian  Polyzoa  belong,  however,  to 
the  great  and  important  Palaeozoic  group  of  the  Lace-corals 
(Fenestella,  figs.  92  and  94,  Retepora,  fig.  93,  Polypora,  and 


DEVONIAN  AND  OLD  RED  PERIOD.  149 

their  allies).  In  all  these  forms  there  is  a  horny  skeleton,  of  a 
fan-like  or  funnel-shaped  form,  which  grew  attached  by  its 
base  to  some  foreign  body.  The  frond  consists  of  slightly- 
diverging  or  nearly  parallel  branches,  which  are  either  united 
by  delicate  cross-bars,  or  which  bend  alternately  from  side  to 
side,  and  become  directly  united  with  one  another  at  short 
intervals — in  either  case  giving  origin  to  numerous  oval  or 
oblong  perforations,  which  communicate  to  the  whole  plant- 
like  colony  a  characteristic  netted  and  lace-like  appearance. 
On  one  of  its  surfaces — sometimes  the  internal,  sometimes  the 
external — the  frond  carries  a  number  of  minute  chambers  or 
"  cells, "  which  are  generally  borne  in  rows  on  the  branches, 
and  of  which  each  originally  contained  a  minute  animal. 


Fig.   95.  —  Spirifera 

sculptilis.  Devonian,  Ca-  Fig.  96.— Spirifera  mucronata.    Devonian,   America, 

nada.    (After  Billings.)  (After  Billings.) 


The  Brachiopods  still  continue  to  be  represented  in  great 
force  through  all  the  Devonian  deposits,  though  not  occurring 
in  the  true  Old  Red  Sandstone.  Besides  such  old  types  as 
Orthis,  Strophomena,  Lingula,  Athyris,  and  Rhynchonella,  we 
find  some  entirely  new  ones ;  whilst  various  types  which  only 
commenced  their  existence  in  the  Upper  Silurian,  now  under- 
go a  great  expansion  and  development.  This  last  is  especially 
the  case  with  the  two  families  of  the  Spiriferidce  and  the  Pro- 
ductida.  The  Spirifers,  in  particular,  are  especially  character- 
istic of  the  Devonian,  both  in  the  Old  and  New  Worlds — some 
of  th6  most  typical  forms,  such  as  Spirifera  mucronata  (fig.  96), 
having  the  shell  "  winged, "  or  with  the  lateral  angles  prolonged 
to  such  an  extent  as  to  have  earned  for  them  the  popular  name 
of  "  fossil-butterflies. "  The  closely-allied  Spirifera  disjuncta 
occurs  in  Britain,  France,  Spain,  Belgium,  Germany,  Russia, 
and  China.  The  family  of  the  Productida  commenced  to  exist 
in  the  Upper  Silurian,  in  the  genus  Chonetes;  and  we  shall 
hereafter  find  it  culminating  in  the  Carboniferous  in  many 


ISO  HISTORICAL  PALAEONTOLOGY. 

forms  of  the  great  genus  Producta  *  itself.  In  the  Devonian 
period,  there  is  an  intermediate  state  of  things,  the  genus 
Chonetes  being  continued  in  new  and  varied  types,  and  the 
Carboniferous  Producta  being  represented  by  many  forms  of 
the  allied  group  Productella.  Amongst  other  well-known  De- 
vonian Brachiopods  may  be  mentioned  the  two  Iong7lived  and 
persistent  types  Atrypa  reticularis  (fig.  97)  and  Strophomena 
rhomboidalis  (fig.  98).  The  former  of  these  commences  in  the 
Upper  Silurian,  but  is  more  abundantly  developed  in  the  De- 
vonian, having  a  geographical  range  that  is  nothing  less  than 


Fig.  97  —Atrypa  reticularis.    Upper  Silurian  and  Devonian  of  Europe 
and  America.    (After  Billings.) 

world-wide;  whilst  the  latter  commences  in  the  Lower  Silurian, 
and,  with  an  almost  equally  cosmopolitan  range,  survives  into 
the  Carboniferous  period. 

The  Bivalves   (Lamellibranchiata}  of  the  Devonian  call  for 


Fig.  98. — Strophomena  rhomboidalia.     Lower  Silurian,  Upper  Silurian,  and 
Devonian  of  Europe  and  America. 

no  special  comment,  the  genera  Pterinea  and  Megalodon  being, 
perhaps,  the  most  noticeable.  The  Univalves  (Gasteropods), 
also,  need  not  be  discussed  in  detail,  though  many  interesting 

*  The  name  of  this  genus  is  often  written  Productus,  just  as  Spirifera 
is  often  given  in  the  masculine  gender  as  Spirifer  (the  name  originally 
given  to  it).  The  masculine  termination  to  these  names  is,  however,  gram- 
matically incorrect,  as  the  feminine  noun  cochlea  (shell)  is  in  these  cases 
understood. 


DEVONIAN  AND  OLD  RED  PERIOD. 


151 


Fig.  99.— Different  views  of  Platyceraa  du- 
mosum,  of  the  natural  size.  Devonian,  Can- 
ada. (Original.) 


forms  of  this  group  are  known.  The  type  most  abundantly 
represented,  especially  in  America,  is  Platyceras  (fig.  99), 

comprising  thin,  wide- 
mouthed  shells,  probably 
most  nearly  allied  to  the 
existing  "  Bonnet-limpets, " 
and  sometimes  attaining 
very  considerable  dimen- 
sions. We  may  also  note 
the  continuance  of  the 
genus  Euomphalus,  with 
its  discoidal  spiral  shell. 
Amongst  the  Heteropods, 
the  survival  of  Bellerophon 
is  to  be  recorded ;  and  in  the  "  Winged-snails, "  or  Pteropods,  we 
find  new  forms  of  the  old  genera  Tentaculites  and  Conularia 
(fig.  100).  The  latter,  with  its  fragile,  conical,  and  often  beauti- 
fully ornamented  shell,  is  especially  noticeable. 

The  remains  of  Cephalopoda  are  far  from  uncommon  in  the 
Devonian  deposits,  all  the  known  forms 
being  still  Tetrabranchiate.  Besides  the 
ancient  types  Orthoceras  and  Cyrtoceras, 
we  have  now  a  predominance  of  the 
spirally-coiled  chambered  shells  of  Goni- 
atites  and  Clymenia.  In  the  former  of 
these  the  shell  is  shaped  like  that  of  the 
Nautilus;  but  the  partitions  between  tbe 
chambers  ("septa")  a're  more  or  less 
lobed,  folded,  or  angulated,  and  the 
"  siphuncle  "  runs  along  the  back  or  con- 
vex side  of  the  shell — these  being  char- 
acters which  approximate  Goniatites  to 
the  true  Ammonites  of  the  later  rocks. 
In  Clymenia,  on  the  other  hand,  whilst 

,,          u   11     /c  \     •  -i    j    •  o  -Fig.   100. — Conularia  or- 

the   shell    (ng.    101)    is   coiled   into   a   flat    nata,  of  the  natural  [size. 

spiral,    and    the    partitions    or    septa    are    De™1^.  Europe, 
simple  or  only  slightly  lobed,  there  is  still 

this  difference,  as  compared  with  the  Nautilus,  that  the  tube  of 
the  siphuncle  is  placed  on  the  inner  or  concave  side  of  the 
shell.  The  species  of  Clymenia  are  exclusively  Devonian  in 
their  range;  and  some  of  the  limestones  of  this  period  in 
Germany  are  so  richly  charged  with  fossils  of  this  genus  as  to 
have  received  the  name  of  "  Clymenien-kalk.  " 


152 


HISTORICAL  PALEONTOLOGY. 


The  sub-kingdom  of  the  Vertebrates  is  still  represented  by 
Fishes  only ;  but  these  are  so  abundant,  and  belong  to  such 
varied  types,  that  the  Devonian  period  has  been  appropriately 
called  the  "  Age  of  Fishes. "  Amongst  the  existing  fishes  there 
are  three  great  groups  which  are  of  special  geological  impor- 
tance, as  being  more  or  less  extensively  represented  in  past  time. 
These  groups  are:  (i)  The  Bony  Fishes  (Teleostei},  comprising 
most  existing  fishes,  in  which  the  skeleton  is  more  or  less  com- 
pletely converted  into  bone;  the  tail  is  symmetrically  lobed  or 
divided  into  equal  moieties;  and  the  scales  are  usually  thin, 
horny,  flexible  plates,  which  overlap  one  another  to  a  greater 


Fig.  101. — Clymenia  SedgwickU .    Devonian,  Europe. 

or  less  extent.  (2)  The  Ganoid  Fishes  (Ganoidei),  comprising 
the  modern  Gar-pikes,  Sturgeons,  &c.,  in  which  the  skeleton 
usually  more  or  less  completely  retains  its  primitive  soft  and 
cartilaginous  condition ;  the  tail  is  generally  markedly  unsym- 
metrical,  being  divided  into  two  unequal  lobes ;  and  the  scales 
(when  present)  have  the  form  of  plates  of  bone,  usually  cov- 
ered by  a  layer  of  shining  enamel.  These  scales  may  overlap; 
or  they  may  be  rhomboidal  plates,  placed  edge  to  edge  in 
oblique  rows;  or  they  have  the  form  of  large-sized  bony  plates, 
which  are  commonly  united  in  the  region  of  the  head  to  form 
a  regular  buckler.  (3)  The  Placoid  Fishes,  or  Elasmobranchii, 


DEVONIAN  AND  OLD  RED  PERIOD.  153 

comprising  the  Sharks,  Rays,  and  Chimcerce  of  the  present  day, 
in  which  the  skeleton  is  cartilaginous ;  the  tail  is  unsymmetric- 
ally  lobed;  and  the  scales  have  the  form  of  detached  bony 
plates  of  variable  size,  scattered  in  the  integument. 

It  is  to  the  two  last  of  these  groups  that  the  Devonian  fishes 
belong,  and  they  are  more  specially  referable  to  the  Ganoids. 
The  order  of  the  Ganoid  fishes  at  the  present  day  comprises 
by  some  seven  or  eight  genera,  the  species  of  which  princi- 
pally or  exclusively  inhabit  fresh  waters,  and  all  of  which  are 
confined  to  the  northern  hemisphere.  As  compared,  there- 
fore, with  the  Bony  fishes,  which  constitute  the  great  majority 
of  existing  forms,  the  Ganoids  form  but  an  extremely  small  and 
limited  group.  It  was  far  otherwise,  however,  in  Devonian 
times.  At  this  period,  the  bony  fishes  are  not  known  to  have 
come  into  existence  at  all,  and  the  Ganoids  held  almost  undis- 
puted possession  of  the  waters.  To  what  extent  the  Devonian 
Ganoids  were  confined  to  fresh  waters  remains  yet  to  be  proved ; 
and  that  many  of  them  lived  in  the  sea  fs  certain.  It  was 
formerly  supposed  that  the  Old  Red  Sandstone  of  Scotland 
and  Ireland,  with  its  abundant  fish-remains,  might  perhaps  be 
a  fresh-water  deposit,  since  the  habitat  of  its  fishes  is  uncer- 
tain, and  it  contains  no  indubitable  marine  fossils.  It  has 
been  now  shown,  however,  that  the  marine  Devonian  strata  of 
Devonshire  and  the  continent  of  Europe  contain  some  of  the 
most  characteristic  of  the  Old  Red  Sandstone  fishes  of  Scot- 
land; whilst  the  undoubted  marine  deposit  of  the  Corniferous 
limestone  of  North  America  contains  numerous  shark-like  and 
Ganoid  fishes,  including  such  a  characteristic  Old  Red  genus 
as  Coccosteus.  There  can  be  little  doubt,  therefore,  but  that  the 
majority  of  the  Devonian  fishes  were  truly  marine  in  their  habits, 
though  it  is  probable  that  many  of  them  lived  in  shallow  water, 
in  the  immediate  neighborhood  of  the  shore,  or  in  estuaries. 

The  Devonian  Ganoids  belong  to  a  number  of  groups;  and 
it  is  only  possible  to  notice  a  few  of  the  most  important  forms 
here.  The  modern  group  of  the  Sturgeons  is  represented, 
more  or  less  remotely,  by  a  few  Devonian  fishes — such  as  As- 
terosteus;  and  the  great  Macro petalichthys  of  the  Corniferous 
limestone  of  North  America  is  believed  by  Newberry  to  belong 
to  this  group.  In  this  fish  (fig.  102,  fr)  the  skull  was  of  large 
size,  its  outer  surface  being  covered  with  a  tuberculated  enamel ; 
and,  as  in  the  existing  Sturgeons,  the  mouth  seems  to 
have  been  wholly  destitute  of  teeth.  Somewhat  allied,  also,  to 
the  Sturgeons,  is  a  singular  group  of  armored  fishes,  which  is 


154 


HISTORICAL  PALEONTOLOGY. 


highly  characteristic  of  the  Devonian  of  Britain  and  Europe, 
and  less  so  of  that  of  America.  In  these  curious  forms  the 
head  and  front  extremity  of  the  body  were  protected  by  a 
buckler  composed  of  large  enameled  plates,  more  or  less 
firmly  united  to  one  another;  whilst  the  hinder  end  of  the  body 
was  naked,  or  was  protected  with  small  scales.  Some  forms  of 


Fig.  102.— Fishes  of  the  Devonian  rocks  of  America,  a,  Diagram  of  the  jaws  and 
teeth  of  Dinichthys  Hertzeri,  viewed  from  the  front,  and  greatly  reduced  ;  6,  Diagram 
of  the  skull  of  Macropetalichthys  Sullivanti,  reduced  In  size  ;  c,  A  portion  of  the  en- 
amelled surface  of  the  skull  of  the  same,  magnified  ;  d,  One  of  the  scales  of  Onychodus 
sigmoides,  of  the  natural  size  ;  e,  One  of  the  front  teeth  of  the  lower  jaw  of  the  same, 
of  the  natural  size  ;  /,  Fin-spine  of  MachoRracanthus  major,  a  shark-like  fish  reduced 
In  size.  (After  Newberry.; 

this  group — such  as  Pteraspis  and  Coccosteus — date  from  the 
Upper  Silurian;  but  they  attain  their  maximum  in  the  Devo- 
nian, and  none  of  them  are  known  to  pass  upwards  into  the 
overlying  Carboniferous  rocks.  Amongst  the  most  character- 
istic forms  of  this  group  may  be  mentioned  Cephalaspis  (fig. 
103)  and  Pterichthys  (fig.  104).  In  the  former  of  these  the 


DEVONIAN  AND  OLD  RED  PERIOD.  155 

head-shield  is  of  a  crescentic  shape,  having  its  hinder  angles 
produced  backwards  into  long  "  horns,  "  giving  it  the  shape  of 
a  "  saddler's  knife.  "  No  teeth  have  been  discovered ;  but  the 
body  was  covered  with  small  ganoid  scales,  and  there  was  an 
unsymmetrical  tail-fin.  In  Pterichthys — which,  like  the  preced- 
ing, was  first  brought  to  light  by  the  labors  of  Hugh  Miller — 
the  whole  of  the  head  and  the  front  part  of  the  body  were  de- 
fended by  a  buckler  of  firmly-united  enamelled  plates,  whilst 
the  rest  of  the  body  was  covered  with  small  scales.  The  form 
of  the  "pectoral  fins"  was  quite  unique — these  having  the 
shape  of  two  long,  curved  spines,  somewhat  like  wings,  covered 
by  finely-tuberculated  ganoid  plates.  All  the  preceding  forms 
of  this  group  are  of  small  size;  but  few  fishes,  living  or  extinct, 
could  rival  the  proportions  of  the  great  Dinichthys,  referred  to 


Fig.  103.— Cephalaspia  Lyellii.    Old  Red  Sandstone,  Scotland.    (After  Page.) 

this  family  by  Newberry.  In  this  huge  fish  (fig.  102,  a)  the 
head  alone  is  over  three  feet  in  length,  and  the  body  is  sup- 
posed to  have  been  twenty-five  or  thirty  feet  long.  The  head 
was  protected  by  a  massive  cuirass  of  bony  plates  firmly  articu- 
lated together,  but  the  hinder  end  of  the  body  seems  to  have 
been  simply  enveloped  in  a  leathery  skin.  The  teeth  are  of 
the  most  formidable  description,  consisting  in  both  jaws  of 
serrated  dental  plates  behind,  and  in  front  of  enormous  coni- 
cal tusks  (fig.  102,  a).  Though  immensely  larger,  the  teeth  of 
Dinichthys  present  a  curious  resemblance  to  those  of  the  exist- 
ing Mud-fishes  (Lepidosiren}. 

In  another  great  group  of  Devonian  Ganoids,  we  meet  with 
fishes  more  or  less  closely  allied  to  the  living  Polypteri  (fig. 
105)  of  the  Nile  and  Senegal.  In  this  group  (fig.  106)  the 
pectoral  fins  consist  of  a  central  scaly  lobe  carrying  the  fin- 


156  HISTORICAL  PALAEONTOLOGY. 

rays  on  both  sides,  the  scales  being  sometimes  rounded  and 
overlapping  (fig.  106),  or  more  commonly  rhomboidal  and 
placed  edge  to  edge  (fig.  105,  A).  Numerous  forms  of  these 


Fig.  IQl.—Pterichthys  cornutua.    Old  Bed  Sandstone,  Scotland. 

(After  Agassi z.) 

"  Fringe-finned "  Ganoids  occur  in  the  Devonian  strata,  such 
as  Holoptychius,  Glyptolamus,  Osteolepis,  Phaneropleuron,  &c. 
To  this  group  is  also  to  be  ascribed  the  huge  Onychodus  (fig. 
102,  d  and  e),  with  its  large,  rounded,  overlapping  scales,  an 
inch  in  diameter,  and  its  powerful  pointed  teeth.  It  is  to  be 
remembered,  however,  that  some  of  these  "  Fringe-finned " 
Ganoids  are  probably  referable  to  the  small  but  singular  group 
of  the  "Mud-fishes"  (Dipnoi},  represented  at  the  present  day 
by  the  singular  Lepidosiren  of  South  America  and  Africa,  and 
the  Ceratodus  of  the  rivers  of  Queensland. 

Leaving  the  Ganoid  fishes,  it  still  remains  to  be  noticed  that 
the  Devonian  deposits  have  yielded  the  remains  of  a  number 
of  fishes  more  or  less  closely  allied  to  the  existing  Sharks, 
Rays,  and  Chimccrce  (the  Elasmobranchii).  The  majority  of 
the  forms  here  alluded  to  are  allied  not  to  the  true  Sharks  and 
Dog-fishes,  but  to  the  more  peaceable  u  Port  Jackson  Sharks, " 
with  their  blunt  teeth,  adapted  for  crushing  the  shells  of  Mol- 
luscs. The  collective  name  of  "  Cestracionts "  is  applied  to 
these;  and  we  have  evidence  of  their  past  existence  in  the 
Devonian  seas  both  by  their  teeth,  and  by  the  defensive  spines 
which  were  implanted  in  front  of  a  greater  or  less  number  of 
the  fins.  These  are  bony  spines,  often  variously  grooved, 
serrated,  or  ornamented,  with  hollow  bases,  implanted  in  the 
integument,  and  capable  of  being  erected  or  depressed  at  will. 
Many  of  these  "  fin-spines "  have  been  preserved  to  us  in  the 
fossil  condition,  and  the  Devonian  rocks  have  yielded  examples 
belonging  to  many  genera.  As  some  of  the  true  Sharks  and 


DEVONIAN  AND  OLD  RED  PERIOD. 


157 


Dog-fishes,  some  of  the  Ganoids,  and  even  some  Bony  fishes, 
possess  similar  defences,  it  is  often  a  matter  of  some  uncer- 
tainty to  what  group  a  given  spine  is  to  be  referred.  One  of 
these  spines,  belonging  to  the  genus  Machcer  acanthus,  from  the 
Devonian  rocks  of  America,  has  been  figured  in  a  previous 
illustration  (fig.  102,  /). 

In  conclusion,  a  very  few  words  may  be  said  as  to  the 
validity  of  the  Devonian  series  as  an  independent  system  of 
rocks,  preserving  in  its  successive  strata  the  record  of  an 
independent  system  of  life.  Some  high  authorities  have  been 
inclined  to  the  view  that  the  Devonian  formation  has  in  nature 
no  actual  existence,  but  that  it  is  made  up  partly  of  beds 
which  should  be  referred  to  the  summit  of  the  Upper  Silurian, 


B 


Fig.  105.— A,  Polypterus,  a  recent  Ganoid  fish  ;  B.  Osteolepis,  a  Devonian  Ganoid 
a,  a,  Pectoral  fins,  showing  the  fin-rays  arranged  round  a  central  lobe. 


and  partly  of  beds  which  properly  belong  to  the  base  of  the 
Carboniferous.  This  view  seems  to  have  been  arrived  at  in 
consequence  of  a  too  exclusive  study  of  the  Devonian  series 
of  the  British  Isles,  where  the  physical  succession  is  not  wholly 
clear,  and  where  there  is  a  striking  discrepancy  between  the 
organic  remains  of  those  two  members  of  the  series  which  are 
known  as  the  "  Old  Red  Sandstone "  and  the  "  Devonian " 
rocks  proper.  This  discrepancy,  however,  is  not  complete; 
and,  as  we  have  seen,  can  be  readily  explained  on  the  sup- 
position that  the  one  group  of  rocks  presents  us  with  the 


158  HISTORICAL  PALEONTOLOGY. 

shallow  water  and  littoral  deposits  of  the  period,  while  in  the 
other  we  are  introduced  to  the  deep-sea  accumulations  of  the 
same  period.  Nor  can  the  problem  at  issue  be  solved  by  an 
appeal  to  the  phenomena  of  the  British  area  alone,  be  the 
testimony  of  these  what  it  may.  As  a  matter  of  fact,  there  is 
at  present  no  sufficient  ground  for  believing  that  there  is  any 
irreconcilable  discordance  between  the  succession  of  rocks 
and  of  life  in  Britain  during  the  period  which  elapsed  between 
the  deposition  of  the  Upper  Ludlow  and  the  formation  of  the 


Fig.  lOG.—Holoptycfiius  nobiliasimn*,  restored.    Old  Red  Sandstone,  Scotland. 
A,  Scale  of  the  same. 


Carboniferous  Limestone,  and  the  order  of  the  same  phe- 
nomena during  the  same  period  in  other  regions.  Sohie  of 
the  Devonian  types  of  life,  as  is  the  case  with  all  great  forma- 
tions, have  descended  unchanged  from  older  types ;  others 
pass  upwards  unchanged  to  the  succeeding  period:  but  the 
fauna  and  flora  of  the  Devonian  period  are,  as  a  whole,  quite 
distinct  from  those  of  the  preceding  Silurian  or  the  succeeding 
Carboniferous;  and  they  correspond  to  an  equally  distinct 
rock-system,  which  in  point  of  time  holds  an  intermediate 
position  between  the  two  great  groups  just  mentioned.  As 
before  remarked,  this  conclusion  may  be  regarded  as  suffi- 
ciently proved  even  by  the  phenomena  of  a  British  area ; 
but  it  may  be  said  to  be  rendered  a  certainty  by  the  study  of 
the  Devonian  deposits  of  the  continent  of  Europe — or,  still 
more,  by  the  investigation  of  the  vast,  for  the  most  part  un- 
interrupted and  continuous  series  of  sediments  which  com- 
menced to  be  laid  down  in  North  America  at  the  beginning  of 
the  Upper  Silurian,  and  did  not  cease  till,  at  any  rate,  the  close 
of  the  Carboniferous. 


DEVONIAN  AND  OLD  RED  PERIOD.  159 

LITERATURE. 

The  following  list  comprises  the  more  important  works  and 
memoirs  to  which  the  student  of  Devonian  rocks  and  fossils 
may  refer: — 

(1)  '  Siluria. '     Sir  Roderick  Murchison. 

(2)  '  Geology   of   Russia  in   Europe. '     Murchison    (together 

with  De  Verneuil  and  Count  von  Keyserling). 

(3)  "  Classification  of  the  Older  Rocks  of  Devon  and  Corn- 
wall " — '  Proc.  Geol.  Soc., '  vol.  iii.,  1839.     Sedgwick  and 
Murchison. 

(4)  "  On  the  Physical  Structure  of  Devonshire ;  "  and  on  the 

"  Classification  of  the  Older  Stratified  Rocks  of  Devon- 
shire and  Cornwall"— '  Trans.  Geol.  Soc.,'  vol.  v.,  1840. 
Sedgwick  and  Murchison. 

(5)  "On  the  Distribution  and  Classification  of  the  Older  or 

Palaeozoic  Rocks  of  North  Germany  and  Belgium " — 
'Geol.  Trans.,'  2d  ser.,  vol.  vi.,  1842.  Sedgwick  and 
Murchison. 

(6)  'Report  on  the  Geology  of  Cornwall,  Devon,  and  West 

Somerset.'  De  la  Beche. 

(7)  '  Memoirs  of  the  Geological  Survey  of  Ireland  and  Scot- 

land.'    Jukes  and  Geikie. 

(8)  "  On  the  Carboniferous  Slate  (or  Devonian  Rocks)  and 

the  Old  Red  Sandstone  of  South  Ireland  and  North 
Devon  " — '  Quart.  Journ.  Geol.  Soc., '  vol.  xxii.  Jukes. 

(9)  "  On  the  Physical  Structure  of  West  Somerset  and  North 

Devon ; "  and  on  the  "  Palaeontological  Value  of  De- 
vonian Fossils " — '  Quart.  Journ.  Geol.  Soc., '  vol.  iii. 
Etheridge. 

(10)  "  On  the  connection  of  the  Lower,  Middle,  and  Upper 

Old  Red  Sandstone  of  Scotland "—' Trans.  Edin.  Geol. 
Soc.,'  vol.  i.  part  ii.  Powrie. 

(11)  '  The  Old  Red  Sandstone, ' '  The  Testimony  of  the  Rocks, ' 

and  '  Footprints  of  the  Creator. '    Hugh  Miller. 

(12)  "Report  on   the  4th   Geological   District" — 'Geology   of 

New  York. '  vol.  iv.    James  Hall. 

(13)  'Geology  of  Canada,'  1863.    Sir  W.  E.  Logan. 

Acadian  Geology.'    Dawson. 
Manual  of  Geology. '    Dana. 


(1 


Geological  Survey  of  Ohio, '  vol.  i. 


Geological  Survey  of  Illinois, '  vol  i. 

(18)  '  Palaeozoic  Fossils  of  Cornwall,  Devon,  and  West  Somer- 

set. '     Phillips. 

(19)  '  Recherches  sur  les  Poissons  Fossiles. '    Agassiz. 

(20)  '  Poissons  de  1'Old  Red. '    Agassiz. 

(21)  "On    the    Classification    of    Devonian    Fishes" — 'Mem. 

Geol.  Survey  of  Great  Britain. '  Decade  X.     Huxley. 

(22)  '  Monograph  of  the  Fishes  of  the  Old  Red  Sandstone  of 

Britain'  (Palaeontographical  Society).    Powrie  and  Lan- 
kester. 

(23)  '  Fishes  of  the  Devonian  System,  Palaeontology  of  Ohio. ' 

Newberry. 


160  HISTORICAL  PALEONTOLOGY. 

(24)  'Monograph   of   British   Trilobites'    (  Palaeontographical 

Society).     Salter. 

(25)  'Monograph  of   British   Merostomata '    (  Palaeontograph- 

ical  Society).    Henry  Woodward. 

(26)  'Monograph   of    British    Brachiopoda'    ( Palaeontograph- 

ical  Society).  .Davidson. 

(27)  '^Monograph   of    British   Fossil   Corals'    Palaeontograph- 

ical  Society).     Milne-Edwards  and  Haime. 

(28)  'Polypiers    Foss.    des    Terrains    Paleozoiques. '      Milne- 

Edwards  and  Jules  Haime. 

(29)  "Devonian  Fossils  of  Canada  West "— '  Canadian  Jour- 
nal, '  new  sen,  vols.  iv.-vi    Billings. 

(30)  '  Palaeontology  of  New  York, '  vol.  iv.    James  Hall. 

(31)  'Thirteenth,  Fifteenth,  and  Twenty-third  Annual  Reports 

on  the  State  Cabinet. '    James  Hall. 

(32)  '  Palaeozoic  Fossils  of  Canada, '  vol.  ii.    Billings. 

(33)  'Reports  on  the  Palaeontology  of  the  Province  of  Ontario 

for  1874  and  1875. '     Nicholson. 

(34)  "The  Fossil  Plants  of  the  Devonian  and  Upper  Silurian 

Formations    of    Canada "— '  Geol.    Survey    of    Canada. ' 
Dawson. 

(35)  '  Petrefacta  Germaniae. '    Goldfuss. 

(36)  '  Versteinerungen  der  Grauwacken-formation. '  &c.  Geinitz. 

(37)  '  Beitrag     zur     Palaeontologie     des     Thuringer-Waldes. ' 
Richter  and  Unger. 

(38)  '  Ueber    die    Placodermen    des    Devonischen    Systems. ' 

Pander. 

(39)  '  Die  Gattungen  der  Fossilen  Pflanzen. '     Goeppert. 

(40)  '  Genera  et  Species  Plantarum  Fossilium. '    Unger. 


CHAPTER  XII. 

THE  CARBONIFEROUS  PERIOD. 

Overlying  the  Devonian  formation  is  the  great  and  impor- 
tant series  of  the  Carboniferous  Rocks,  so  called  because  workable 
beds  of  coal  are  more  commonly  and  more  largely  developed 
in  this  formation  than  in  any  other.  Workable  coal-seams, 
however,  occur  in  various  other  formations  (Jurassic,  Cretace- 
ous, Tertiary),  so  that  coal  is  not  an  exclusively  Carboniferous 
product;  whilst  even  in  the  Coal-measures  themselves  the  coal 
bears  but  a  very  small  proportion  to  the  total  thickness  of 
strata,  occurring  only  in  comparatively  thin  beds  intercalated 
in  a  great  series  of  sandstones,  shales,  and  other  genuine 
aqueous  sediments. 


THE  CARBONIFEROUS  PERIOD.  161 

Stratigraphically,  the  Carboniferous  rocks  usually  repose 
conformably  upon  the  highest  Devonian  beds,  so  that  the  line 
of  demarcation  between  the  Carboniferous  and  Devonian  for- 
mations is  principally  a  palaeontological  one,  founded  on  the 
observed  differences  in  the  fossils  of  the  two  groups.  On  the 
other  hand,  the  close  of  the  Carboniferous  period  seems  to 
have  been  generally,  though  not  universally,  signalized  by 
movements  of  the  crust  of  the  earth,  so  that  the-  succeeding 
Permian  beds  often  lie  unconformably  upon  the  Carboniferous 
sediments. 

Strata  of  Carboniferous  age  have  been  discovered  in  almost 
every  large  land-area  which  has  been  sufficiently  investigated; 
but  they  are  especially  largely  developed  in  Britain,  in  various 
parts  of  the  continent  of  Europe,  and  in  North  America. 
Their  general  composition,  however,  is,  comparatively  speak- 
ing, so  uniform,  that  it  will  suffice  to  take  a  comprehensive 
view  of  the  formation  without  considering  any  one  area  in 
detail,  though  in  each  region  the  subdivisions  of  the  formation 
are  known  by  distinctive  local  names.  Taking  such  a  com- 
prehensive view,  it  is  found  that  the  Carboniferous  series  is 
generally  divisible  into  a  Loiver  and  essentially  calcareous 
group  (the  "  Sub-Carboniferous "  or  "  Carboniferous  Lime- 
stone"); a  Middle  and  principally  arenaceous  group  (the 
"  Millstone  Grit ")  ;  and  an  Upper  group,  of  alternating  shales 
and  sandstones,  with  workable  seams  of  coal  (the  "  Coal- 
measures  "). 

I.  The  Carboniferous.  Sub-Carboniferous,  or  Mountain  Lime- 
stone Series  constitutes  the  general  base  of  the  Carboniferous 
system.  As  typically  developed  in  Britain,  the  Carboniferous 
Limestone  is  essentially  a  calcareous  formation,  sometimes 
consisting  of  a  mass  of  nearly  pure  limestone  from  1000  to 
2000  feet  in  thickness,  or  at  other  times  of  successive  great 
beds  of  limestone  with  subordinate  sandstones  and  shales. 
In  the  north  of  England  the  base  of  the  series  consists  of 
pebbly  conglomerates  and  coarse  sandstones;  and  in  Scot- 
land generally,  the  group  is  composed  of  massive  sandstones 
with  a  comparatively  feeble  development  of  the  calcareous 
element.  In  Ireland,  again,  the  base  of  the  Carboniferous 
Limestone  is  usually  considered  to  be  formed  by  a  locally- 
developed  group  of  grits  and  shales  (the  "  Coomhola  Grits " 
and  "Carboniferous  Slate"),  which  attain  the  thickness  of 
about  5000  feet,  and  contain  an  intermixture  of  Devonian 
with  Carboniferous  types  of  fossils.  Seeing  that  the  Devonian 


162  HISTORICAL  PALEONTOLOGY. 

formation  is  generally  conformable  to  the  Carboniferous,  we 
need  feel  no  surprise  at  this  intermixture  of  forms;  nor  does  it 
appear  to  be  of  great  moment  whether  these  strata  be  referred 
to  the  former  or  to  the  latter  series.  Perhaps  the  most  satis- 
factory course  is  to  regard  the  Coomhola  Grits  and  Carbon- 
iferous Slates  as  "passage-beds"  between  the  Devonian  and 
Carboniferous;  but  any  view  that  may  be  taken  as  to  the 
position  of  these  beds,  really  leaves  unaffected  the  integrity 
of  the  Devonian  series  as  a  distinct  life-system,  which,  on  the 
whole,  is  more  closely  allied  to  the  Silurian  than  to  the  Car- 
boniferous. In  North  America,  lastly,  the  Sub-Carboniferous 
series  is  never  purely  calcareous,  though  in  the  interior  of  the 
continent  it  becomes  mainly  so.  In  other  regions,  however, 
it  consists  principally  of  shales  and  sandstones,  with  subor- 
dinate beds  of  limestone,  and  sometimes  with  thin  beds  of 
coal  or  deposits  of  clay-ironstone. 

II.  The  Millstone   Grit.— The   highest  beds   of  the   Carbon- 
iferous Limestone  series  are  succeeded,  generally  with  perfect 
conformity,  by  a  series  of  arenaceous  beds,  usually  known  as 
the    Millstone    Grit.      As    typically    developed    in    Britain,    this 
group   consists   of   hard   quartzose    sandstones,    often    so    large- 
grained    and   coarse   in    texture    as    to    properly   constitute    fine 
conglomerates.      In    other    cases    there    are    regular    conglomer- 
ates, sometimes  with  shales,  limestones,  and  thin  beds  of  coal — 
the  thickness  of  the  whole  series,  when  well  developed,  varying 
from    1000    to    5000    feet.      In    North    America,    the    Millstone 
Grit  rarely  reaches   1000   feet  in   thickness;   and,  like  its   Brit- 
ish  equivalent,   consists   of  coarse   sandstones   and  grits,   some- 
times  with    regular    conglomerates.      Whilst    the    Carboniferous 
Limestone    was    undoubtedly    deposited    in     a    tranquil    ocean 
of  considerable  depth,  the  coarse  mechanical  sediments  of  the 
Millstone      Grit      indicate      the      progressive      shallowing      of 
the     Carboniferous     seas,     and     the     consequent     supervention 
of  shore-conditions. 

III.  The    Coal-measures. — The    Coal-measures    properly    so 
called   rest   conformably   upon   the    Millstone   Grit,   and   usually 
consist  of  a  vast  series  of  sandstones,  shales,  grits,  and  coals, 
sometimes  with  beds  of  limestone,  attaining  in  some  regions  a 
total   thickness   of   from   7000  to   nearly    14,000   feet.     Beds   of 
workable  coal  are  by  no  means  unknown  in  some  areas  in  the 
inferior  group  of  the  Sub-Carboniferous;  but  the  general  state- 
ment is  true,  that  coal  is  mostly  obtained  from  the  true  Coal- 
measures — the    largest    known,    and    at    present    most    produc- 


THE  CARBONIFEROUS  PERIOD.  163 

tive  coal-fields  of  the  world  being  in  Great  Britain,  North 
America,  and  Belgium.  Wherever  they  are  found,  with 
limited  exceptions,  the  Coal-measures  present  a  singular 
general  uniformity  of  mineral  composition.  They  consist, 
namely,  of  an  indefinite  alternation  of  beds  of  sandstone, 
shale,  and  coal,  sometimes  with  bands  of  clay-ironstone  or  beds 
of  limestone,  repeated  in  no  constant  order,  but  sometimes 
attaining  the  enormous  aggregate  thickness  of  14,000  feet,  or 
little  short  of  3  miles.  The  beds  of  coal  differ  in  number  and 
thickness  in  different  areas,  but  they  seldom  or  never  exceed 
one-fiftieth  part  of  the  total  bulk  of  the  formation  in  thickness. 
The  characters  of  the  coal  itself,  and  the  way  in  which  the 
coal-beds  were  deposited,  will  be  briefly  alluded  to  in  speaking 
of  the  vegetable  life  of  the  period.  In  Britain,  and  in  the  Old 
World  generally,  the  Coal-measures  are  composed  partly  of 
genuine  terrestrial  deposits — such  as  the  Coal — and  partly  of 
sediments  accumulated  in  the  fresh  or  brackish  waters  of  vast 
lagoons,  estuaries,  and  marshes.  The  fossils  of  the  Coal- 
measures  in  these  regions  are  therefore  necessarily  the  remains 
either  of  terrestrial  plants  and  animals,  or  of  such  forms  of 
life  as  inhabit  fresh  or  brackish  waters,  the  occurrence  of  strata 
with  marine  fossils  being  quite  a  local  and  occasional  phe- 
nomenon. In  various  parts  of  North  America,  on  the  other 
hand,  the  Coal-measures,  in  addition  to  sandstones,  shales, 
coal-seams,  and  bands  of  clay-ironstone,  commonly  include 
beds  of  limestone,  charged  with  marine  remains,  and  indicating 
marine  conditions.  The  subjoined  section  (fig.  107)  gives,  in 
a  generalized  form,  the  succession  of  the  Carboniferous  strata 
in  such  a  British  area  as  the  north  of  England,  where  the  series 
is  developed  in  a  typical  form. 

As  regards  the  life  of  the  Carboniferous  period,  we  naturally 
find,  as  has  been  previously  noticed,  great  differences  in  dif- 
ferent parts  of  the  entire  series,  corresponding  to  the  different 
mode  of  origin  of  the  beds.  Speaking  generally,  the  Lower 
Carboniferous  (or  the  Sub-Carboniferous)  is  characterized  by 
the  remains  of  marine  animals;  whilst  the  Upper  Carbon- 
iferous (or  Coal-measures)  is  characterized  by  the  remains 
of  plants  and  terrestrial  animals.  In  all  those  cases,  how- 
ever, in  which  marine  beds  are  found  in  the  series  of  the 
Coal-measures,  as  is  common  in  America,  then  we  find  that  the 
fossils  agree  in  their  general  characters  with  those  of  the  older 
marine  deposits  of  the  period. 

Owing  to  the  fact  that  coal  is  simply  compressed  and  other- 


1 64 


HISTORICAL  PALEONTOLOGY. 


wise  altered  vegetable  matter,  and  that  it  is  of  the  highest 
economic  value  to  man,  the  Coal-measures  have  been  more 
thoroughly  explored  than  any  other  group  of  strata  of  equiva- 

GENERALIZED  SECTION  OF  THE  CARBONIFEROUS  STRATA 
OF  THE  NORTH  OF  ENGLAND. 


Fig.  107. 


Permian      (New     Red 
Sandstone). 


> Coal-measures. 


Millstone   Grit. 


Yoredale  Series. 


Scar-Limestone    Series 


Basement  Beds  (Con 
glomerates    and 
Sandstones). 


lent  thickness  in  the  entire  geological   series.     Hence  we  have 
already   a   very  extensive   acquaintance   with   the   plants  of   the 


THE  CARBONIFEROUS  PERIOD.  165 

Carboniferous  period;  and  our  knowledge  on  this  subject  is 
daily  undergoing  increase.  It  is  not  to  be  supposed,  however, 
that  the  remains  of  plants  are  found  solely  in  the  Coal- 
measures;  for  though  most  abundant  towards  the  summit, 
they  are  found  in  less  numbers  in  all  parts  of  the  series. 
Wherever  found,  they  belong  to  the  same  great  types  of  vege- 
tation ;  but,  before  reviewing  these,  a  few  words  must  be  said 
as  to  the  orgin  and  mode  of  formation  of  coal. 

The  coal-beds,  as  before  mentioned,  occur  interstratified 
with  shales,  sandstones,  and  sometimes  limestones;  and  there 
may,  within  the  limits  of  a  single  coal-field,  be  as  many  as  80 
of  100  of  such  beds,  placed  one  above  the  other  at  different 
levels,  and  varying  in  thickness  from  a  few  inches  up  to  20  or 
30  feet.  As  a  general  rule,  each  bed  of  coal  rests  upon  a  bed 
of  shale  or  clay,  which  is  termed  the  "  under-clay, "  and  in 
which  are  found  numerous  roots  of  plants;  whilst  the  strata 
immediately  on  the  top  of  the  coal  may  be  shaly  or  sandy, 
but  in  either  case  are  generally  charged  with  the  leaves  and 
stems  of  plants,  and  often  have  upright  trunks  passing  vertically 
through  them.  When  we  add  to  this  that  the  coal  itself  is, 
chemically,  nearly  wholly  composed  of  carbon,  and  that  its 
microscopic  structure  shows  it  to  be  composed  almost  entirely 
of  fragments  of  stems,  leaves,  bark,  seeds,  and  vegetable  debris 
derived  from  land-plants,  we  are  readily  enabled  to  understand 
how  the  coal  was  formed.  The  "  under-clay "  immediately 
beneath  the  coal-bed  represents  an  old  land-surface — some- 
times, perhaps,  the  bottom  of  a  swamp  or  marsh,  covered 
with  a  luxuriant  vegetation;  the  coal-bed  itself  represents  the 
slow  accumulation,  through  long  periods,  of  the  leaves,  seeds, 
fruits,  stems,  and  fallen  trunks  of  this  vegetation,  now  hardened 
and  compressed  into  a  fraction  of  its  original  bulk  by  the  pres- 
sure of  the  superincumbent  rocks ;  and  the  strata  of  sand  or 
shale  above  the  coal-bed — the  so-called  "  roof "  of  the  coal — 
represent  sediments  quietly  deposited  as  the  land,  after  a  long 
period  of  repose,  commenced  to  sink  beneath  the  sea.  On 
this  view,  the  rank  and  long-continued  vegetation  which  gave 
rise  to  each  coal-bed  was  ultimately  terminated  by  a  slow 
depression  of  the  surface  on  which  the  plants  grew.  The 
land-surface  then  became  covered  by  the  water,  and  aqueous 
sediments  were  accumulated  to  a  greater  or  less  thickness  upon 
the  dense  mass  of  decaying  vegetation  below,  enveloping  any 
trunks  of  trees  which  might  still  be  in  an  erect  position,  and 
preserving  between  their  layers  the  leaves  and  branches  of 


166  HISTORICAL  PALEONTOLOGY. 

plants  brought  down  from  the  neighboring  land  by  streams, 
or  blown  into  the  water  by  the  wind.  Finally,  there  set  in  a 
slow  movement  of  elevation, — the  old  land  again  reappeared 
above  the  water;  a  new  and  equally  luxuriant  vegetation 
flourished  upon  the  new  land-surface ;  and  another  coal-bed 
was  accumulated,  to  be  preserved  ultimately  in  a  similar 
fashion.  Some  few  beds  of  coal  may  have  been  formed  by 
drifted  vegetable  matter  brought  down  into  the  ocean  by  rivers, 
and  deposited  directly  on  the  bottom  of  the  sea;  but  in  the 
majority  of  cases  the  coal  is  undeniably  the  result  of  the  slow 
growth  and  decay  of  plants  in  situ ;  and  as  the  plants  of  the 
coal  are  not  marine  plants,  it  is  necessary  to  adopt  some  such 
theory  as  the  above  to  account  for  the  formation  of  coal- 
seams.  By  this  theory,  as  is  obvious,  we  are  compelled  to 
suppose  that  the  vast  alluvial  and  marshy  flats  upon  which  the 
coal-plants  grew  were  liable  to  constantly-recurring  oscillations 
of  level,  the  successive  land-surfaces  represented  by  the  suc- 
cessive coal-beds  of  any  coal-field  being  thus  successively 
buried  beneath  accumulations  of  mud  or  sand.  We  have  no 
need,  however,  to  suppose  that  these  oscillations  affected  large 
areas  at  the  same  time ;  and  geology  teaches  us  that  local 
elevations  and  depressions  of  the  land  have  been  matters  of 
constant  occurrence  throughout  the  whole  of  past  time. 

All  the  varieties  of  coal  (bituminous  coal,  anthracite,  cannel- 
coal,  &c.)  show  a  more  or  less  distinct  "lamination" — that  is 
to  say,  they  are  more  or  less  obviously  composed  of  successive 
thin  layers,  differing  slightly  in  color  and  texture.  All  the 
varieties  of  coal,  also,  consist  chemically  of  carbon,  with  vary- 
ing proportions  of  certain  gaseous  constituents  and  a  small 
amount  of  incombustible  mineral  or  "  ash. "  By  cutting  thin 
and  transparent  slices  of  coal,  we  are  further  enabled,  by 
means  of  the  microscope,  to  ascertain  precisely  not  only  that 
the  carbon  of  the  coal  is  derived  from  vegetables,  but  also,  in 
many  cases,  what  kinds  of  plants,  and  what  parts  of  these,  enter 
into  the  formation  of  coal.  When  examined  in  this  way,  all 
coals  are  found  to  consist  more  or  less  entirely  of  vegetable 
matter;  but  there  is  considerable  difference  in  different  coals  as 
to  the  exact  nature  of  this.  By  Professor  Huxley  it  has  been 
shown  that  many  of  the  English  coals  consist  largely  of  ac- 
cumulations of  rounded  discoidal  sacs  or  bags,  which  are 
unquestionably  the  seed-vessels  or  "  spore-cases "  of  certain  of 
the  commoner  coal-plants  (such  as  the  Lepidodendra),  The 
best  bituminous  coals  seem  to  be  most  largely  composed  of 


THE  CARBONIFEROUS  PERIOD.  167 

these  spore-cases ;  whilst  inferior  kinds  possess  a  progressively 
increasing  amount  of  the  dull  carbonaceous  substance  which  is 
known  as  "  mineral  charcoal, "  and  which  is  undoubtedly  com- 
posed of  "the  stems  and  leaves  of  plants  reduced  to  little 
more  than  their  carbon. "  On  the  other  hand,  Principal  Daw- 
son  finds  that  the  American  coals  only  occasionally  exhibit 
spore-cases  to  any  extent,  but  consist  principally  of  the  cells, 
vessels,  and  fibres  of  the  bark,  integumentary  coverings,  and 
woody  portions  of  the  Carboniferous  plants. 

The  number  of  plants  already  known  to  have  existed  during 
the  Carboniferous  period  is  so  great,  that  nothing  more  can  be 
done  here  than  to  notice  briefly  the  typical  and  characteristic 
groups  of  these — such  as  the  Ferns,  the  Calamites,  the  Lepido- 
dendroids,  the  Sigillarioids,  and  the  Conifers. 

In  accordance  with  M.  Brongniart's  generalization,  that 
the  Palaeozoic  period  is,  botanically  speaking,  the  "  Age  of 
Acrogens, "  we  find  the  Carboniferous  plants  to  be  still  mainly 
referable  to  the  Flowerless  or  "  Cryptogamous "  division  of  the 
vegetable  kingdom.  The  flowering  or  "  Phanerogamous " 
plants,  which  form  the  bulk  of  our  existing  vegetation,  are  hardly 
known,  with  certainty,  to  have  existed  at  all  in  the  Carbon- 
iferous era,  except  as  represented  by  trees  related  to  the  existing 
Pines  and  Firs,  and  possibly  by  the  Cycads  or  "  false  palms.  "* 
Amongst  the  "  Cryptogams, "  there  is  no  more  striking  or 
beautiful  group  of  Carboniferous  plants  than  the  Ferns.  Re- 
mains of  these  are  found  all  through  the  Carboniferous,  but  in 
exceptional  numbers  in  the  Coal-measures,  and  include  both 
herbaceous  forms  like  the  majority  of  existing  species,  and 
arborescent  forms  resembling  the  living  Tree-ferns  of  New 
Zealand.  Amongst  the  latter,  together  with  some  new  types, 
are  examples  of  the  genera  Psaronius  and  Caulopteris,  both  of 
which  date  from  the  Devonian.  The  simply  herbaceous  ferns 
are  extremely  numerous,  and  belong  to  such  widely-distributed 
and  largely-represented  genera  as  Neuropteris,  Odontopteris  (fig. 
108),  Alethopteris,  Pecopteris,  Sphenopteris,  Hymenophyllites,  &c. 

The  fossils  known  as  Calamites  (fig.  109)  are  very  common 
in  the  Carboniferous  deposits,  and  have  given  occasion  to  an 
abundance  of  research  and  speculation.  They  present  them- 
selves as  prostrate  and  flattened  striated  stems,  or  as  similar 

*  Whilst  the  vegetation  of  the  Coal-period  was  mainly  a  terrestrial  one, 
aquatic  plants  are  not  unknown.  Sea-weeds  (such  as  the  Spirophyton 
cauda-Galli)  are  common  in  some  of  the  marine  strata ;  whilst  coal,  accord- 
ing to  the  researches  of  the  Abbe  Castracane,  is  asserted  commonly  to 
contain  the  siliceous  envelope  of  Diatoms. 


i68  HISTORICAL  PALEONTOLOGY. 

uncompressed  stems  growing  in  an  erect  position,  and  some- 
times attaining  a  length  of  twenty  feet  or  more.  Externally,  the 
stems  are  longitudinally  ribbed,  with  transverse  joints  at  regular 
intervals,  these  joints  giving  origin  to  a  whorl  of  branchlets, 
which  may  or  may  not  give  origin  to  similar  whorls  of  smaller 
branchlets  still.  The  stems,  further,  were  hollow,  with  trans- 
verse partitions  at  the  joints,  and  having  neither  true  wood  nor 
bark,  but  only  a  thin  external  fibrous  shell.  There  can  be  little 
doubt  but  that  the  Catamites  are  properly  regarded  as  colossal 
representatives  of  the  little  Horse-tails  (Equisetacece}  of  the 
present  day.  They  agree  with  these  not  only  in  the  general 
details  of  their  organization,  but  also  in  the  fact  that  the  fruit 
was  a  species  of  cone,  bearing  "  spore-cases "  under  scales. 
According  to  Principal  Dawson,  the  Calamites  "grew  in  dense 


Fig.  lOS.—Odontopteris  Schlothelmii.    Carboniferous,  Europe  and  North  America. 

brakes  on  the  sandy  and  muddy  flats,  subject  to  inundation, 
or  perhaps  even  in  water;  and  they  had  the  power  of  budding 
out  from  the  base  of  the  stem,  so  as  to  form  clumps  of  plants, 
and  also  of  securing  their  foothold  by  numerous  cord-like  roots 
proceeding  from  various  heights  on  the  lower  part  of  the 
stem. " 

The  Lepidodendroids,  represented  mainly  by  the  genus 
Lepidodendron  itself  (fig.  no),  were  large  tree-like  plants, 
which  attain  their  maximum  in  the  Carboniferous  period,  but 


THE  CARBONIFEROUS  PERIOD.  169 

which  appear  to  commence  in  the  Upper  Silurian,  are  well 
represented  in  the  Devonian,  and  survive  in  a  diminished  form 
into  the  Permian.  The  trunks  of  the  larger  species  of  Lepido- 


Tlg.  109.— Catamites  cannatformia .    Carboniferous  Rocks,  Europe  and 
North  America. 

dendron  at  times  reach  a  length  of  fifty  feet  and  upwards,  giv- 
ing off  branches  in   a  regular  bifurcating  manner.     The  bark 


170  HISTORICAL  PALAEONTOLOGY. 

is  marked  with  numerous  rhombic  or  oval  scars,  arranged  in 
quincunx  order,  and  indicating  the  points  where  the  long, 
needle-shaped  leaves  were  formerly  attached.  The  fruit  con- 
sisted of  cones  or  spikes,  carried  at  the  ends  of  the  branches, 
and  consisting  of  a  central  axis  surrounded  by  overlapping 
scales,  each  of  which  supports  a  "  spore-case "  or  seed-vessel. 
These  cones  have  commonly  been  described  under  the  name 
of  Lepidostrobi.  In  the  structure  of  the  trunk  there  is  nothing 
comparable  to  what  is  found  in  existing  trees,  there  being 
a  thick  bark  surrounding  a  zone  principally  composed  of 
"  scalariform  "  vessels,  this  in  turn  enclosing  a  large  central  pith. 
In  their  general  appearance  the  Lipidodendra  bring  to  mind 
the  existing  Araucarian  Pines ;  but  they  are  true  "  Crypto- 
gams, "  and  are  to  be  regarded  as  a  gigantic  extinct  type  of  the 
modern  Club-mosses  (Lycopodiacea).  They  are  amongst  the 
commonest  and  most  characteristic  of  the  Carboniferous 
plants ;  and  the  majority  of  the  "  spore-cases "  so  commonly 
found  in  the  coal  appear  to  have  been  derived  from  the  cones 
of  Lepidodendroids. 

The  so-called  Sigillarioids,  represented  mainly  by  Sigillaria 
itself  (fig.  in),  were  no  less  abundant  and  characteristic  of  the 
Carboniferous  forests  than  the  Lepidodendra.  They  commence 
their  existence,  so  far  as  known,  in  the  Devonian  period,  but 
they  attain  their  maximum  in  the  Carboniferous;  and — unlike 
the  Lepidodendroids — they  are  not  known  to  occur  in  the 
Permian  period.  They  are  comparatively  gigantic  in  size, 
often  attaining  a  height  of  from  thirty  to  fifty  feet  or  more; 
but  though  abundant  and  well  preserved,  great  divergence  of 
opinion  prevails  as  to  their,  true  affinities.  The  name  of  Sigil- 
larioids (Lat  sigilla, 'little  seals  or  images)  is  derived  from  the 
fact  that  the  bark  is  marked  with  seal-like  impressions  or  leaf- 
scars  (fig.  in). 

Externally,  the  trunks  of  Sigillaria  present  strong  longitud- 
inal ridges,  with  vertical  alternating  rows  of  oval  leaf-scars 
indicating  the  points  where  the  leaves  were  originally  attached. 
The  trunk  was  furnished  with  a  large  central  pith,  a  thick 
outer  bark,  and  an  intermediate  woody  zone — composed,  accord- 
ing to  Dawson,  partly  of  the  disc-bearing  fibres  so  characteristic 
of  Conifers ;  but,  according  to  Carruthers,  entirely  made  up  of 
the  "  scalariform "  vessels  characteristic  of  Cryptogams.  The 
size  of  the  pith  was  very  great,  and  the  bark  seems  to  have  been 
the  most  durable  portion  of  the  trunk.  Thus  we  have  evidence 
that  in  many  cases  the  stumps  and  "  stools  "  of  Sigillaria,  stand- 


THE  CARBONIFEROUS  PERIOD.  171 

ing  upright  in  the  old  Carboniferous  swamps,  were  completely 
hollowed  out  by  internal  decay,  till  nothing  but  an  exterior 
shell  of  bark  was  left.  Often  these  hollow  stumps  became 


Fig.  110. — Lepidodendron  Sternbergii,  Carboniferous,  Europe.  The  central  figure 
represents  a  portion  of  the  trunk  with  its  branches,  much  reduced  In  size.  The  right- 
hand  figure  is  a  portion  of  a  branch  with  the  leaves  partially  attached  to  It ;  and  the 
left-hand  figure  represents  the  end  of  a  branch  bearing  a  cone  of  fructification. 

ultimately    filled    up    with    sediment,    sometimes    enclosing    the 
remains    of    galley-worms,    land-snails    or    Amphibians,    which 


172  HISTORICAL  PALEONTOLOGY. 

formerly  found  in  the  cavity  of  the  trunk  a  congenial  home ; 
and  from  the  sandstone  or  shale  now  filling  such  trunks  some 
of  the  most  interesting  fossils  of  the  Coal-period  have  been 
obtained.  There  is  little  certainty  as  to  either  the  leaves  or 
fruits  of  Sigillaria,  and  there  is  equally  little  certainty  as  to  the 
true  botanical  position  of  these  plants.  By  Principal  Dawson 
they  are  regarded  as  being  probably  flowering  plants  allied  to 
the  existing  "  false  palms  "  or  "  Cycads;  "  but  the  high  author- 
ity of  Mr.  Carruthers  is  to  be  quoted  in  support  of  the  belief 
that  they  are  Cryptogamic,  and  most  nearly  allied  to  the  Club- 
mosses. 


Pig.  111.— Fragment  of  the  external  surface  of  Sigillaria  Grceseri,  showing  the  ribs 
and  leaf-scars.  The  left-hand  figure  represents  a  small  portion  enlarged.  Carbon- 
iferous, Europe. 

Leaving  the  botanical  position  of  Sigillaria  thus  undecided, 
we  find  that  it  is  now  almost  universally  conceded  that  the 
fossils  originally  described  under  the  name  of  Stigmaria  are 
the  roots  of  Sigillaria,  the  actual  connection  between  the  two 
having  been  in  numerous  instances  demonstrated  in  an  unmis- 
takable manner.  The  Stigmarice  (fig.  112)  ordinarily  present 
themselves  in  the  form  of  long,  compressed  or  rounded  frag- 
ments, the  external  surface  of  which  is  covered  with  rounded 
pits  or  shallow  tubercles,  each  of  which  has  a  little  pit  or  de- 
pression in  its  center.  From  each  of  these  pits  there  proceeds, 
in  perfect  examples,  a  long  cylindrical  rootlet;  but  in  many 
cases  these  have  altogether  disappeared.  In  their  internal 
structure,  Stigmaria  exhibits  a  central  pith  surrounded  by  a 
sheath  of  scalariform  vessels,  the  whole  enclosed  in  a  cellular 


THE  CARBONIFEROUS  PERIOD. 


173 


envelope.  The  Stiginarice  are  generally  found  ramifying  in 
the  "  under-clay, "  which  forms  the  floor  of  a  bed  of  coal,  and 
which  represents  the  ancient  soil  upon  which  the  Sigillaria  grew. 
The  Lepidodendroids  and  Sigillarioids,  though  the  first  were 
certainly,  and  the  second  possibly,  Cryptogamic  or  flowerless 
plants,  must  have  constituted  the  main  mass  of  the  forests  of 
the  Coal  period;  but  we  are  not  without  evidence  of  the  exist- 
ence at  the  same  time  of  genuine  "  trees, "  in  the  technical 
sense  of  this  term — namely,  flowering  plants  with  large  woody 


Fig.  112.— Stigmariaficoides.    Quarter  natural  size.    Carboniferous. 

stems.  So  far  as  is  certainly  known,  all  the  true  trees  of  the 
Carboniferous  formation  were  Conifers,  allied  to  the  existing 
Pines  and  Firs.  They  are  recognized  by  the  great  size  and 
concentric  woody  rings  of  their  prostrate,  rarely  erect  trunks, 
and  by  the  presence  of  disc-bearing  fibres  in  their  wood,  as 
demonstrated  by  the  microscope;  and  the  principal  genera 
which  have  been  recognized  are  Dadoxylon,  Palaoxylon, 
Araucarioxylon,  and  Pinites.  Their  fruit  is  not  known  with 
absolute  certainty,  unless  it  be  represented,  as  often  conjectured, 
by  Trigonocarpon  (fig.  113).  The  fruits  known  under  this 
name  are  nut-like,  often  of  consider- 
able size,  and  commonly  three-  or  six- 
angled.  They  probably  originally 
possessed  a  fleshy  envelope ;  and  if 
truly  referable  to  the  Conifers,  they 
would  indicate  that  these  ancient 
evergreens  produced  berries  instead 
of  cones,  and  thus  resembled  the 
modern  Yews  rather  than  the  Pines. 
It  seems  further,  that  the  great 
group  of  the  Cycads,  which  are  nearly  allied  to  the  Conifers,  and 


Flgr.  113.  —  Trigonocarpon 
ovatum,  Coal-measures.Brltain. 
(After  Lindley  and  Button.) 


174  HISTORICAL  PALAEONTOLOGY. 

which  attained  such  a  striking  prominence  in  the  Secondary 
period,  probably  commenced  its  existence  during  the  Coal 
period  •  but  these  anticipatory  forms  are  comparatively  few  in 
number,  and  for  the  most  part  of  somewhat  dubious  affinities. 


CHAPTER  XIII. 

THE  CARBONIFEROUS  PERIOD— Continued. 
ANIMAL  LIFE  OF  THE  CARBONIFEROUS. 

We  have  seen  that  there  exists  a  great  difference  as  to  the 
mode  of  origin  of  the  Carboniferous  sediments,  some  being 
purely  marine,  whilst  others  are  terrestrial ;  and  others,  again, 
have  been  formed  in  inland  swamps  and  morasses,  or  in  brack- 
ish-water lagoons,  creeks,  or  estuaries.  A  corresponding  dif- 
ference exists  necessarily  in  the  animal  remains  of  these  de- 
posits, and  in  many  regions  this  difference  is  extremely  well 
marked  and  striking.  The  great  marine  limestones  which 
characterize  the  lower  portion  of  the  Carboniferous  series  in 
Britain,  Europe,  and  the  eastern  portion  of  America,  and  the 
calcareous  beds  which  are  found  high  up  in  the  Carboniferous 
in  the  western  States  of  America,  may,  and  do,  often  contain 
the  remains  of  drifted  plants;  but  they  are  essentially  charac- 
terized by  marine  fossils ;  and  moreover,  they  can  be  demon- 
strated bj  the  microscope  to  be  almost  wholly  composed  of 
the  remains  of  animals  which  formerly  inhabited  the  ocean. 
On  the  other  hand,  the  animal  remains  of  the  beds  accompany- 
ing the  coal  are  typically  the  r'emains  of  air-breathing,  terres- 
trial, amphibious,  or  aerial  animals,  together  with  those  which 
inhabit  fresh  or  brackish  waters.  Marine  fossils  may  be  found 
in  the  Coal-measures,  but  they  are  invariably  confined  to  spe- 
cial horizons  in  the  strata,  and  they  indicate  temporary  depres- 
sions of  the  land  beneath  the  sea.  Whilst  the  distinction  here 
mentioned  is  one  which  cannot  fail  to  strike  the  observer,  it  is 
convenient  to  consider  the  animal  life  of  the  Carboniferous  as 
a  whole :  and  it  is  simply  necessary,  in  so  doing,  to  remember 


THE  CARBONIFEROUS  PERIOD. 


175 


that  the  marine  fossils  are  in  general  derived  from  the  inferior 
portion  of  the  system;  whilst  the  air-breathing,  fresh-water,  and 
brackish-water  forms  are  almost  exclusively  derived  from  the 
superior  portion  of  the  same. 

The  Carboniferous  Protozoans  consist  mainly  of  Foramini- 
fera  and  Sponges,  The  latter  are  still  very  insufficiently  known, 
but  the  former  are  very  abundant,  and  belong  to  very  varied 
types.  Thin  slices  of  the  limestones  of  the  period,  when  ex- 
amined by  the  microscope,  very  commonly  exhibit  the  shells 
of  Foraminifera  in  greater  or  less  plenty.  Some  limestones, 
indeed,  are  made  up  of  little  else  than  these  minute  and  elegant 
shells,  often  belonging  to  types,  such  as  the  Textularians  and 
Rotalians,  differing  little  or  not  at  all  from  those  now  in  exist- 
ence. This  is  the  case,  for  example,  with  the  Carboniferous 
Limestone  of  Spergen  Hill  in  Indiana  (fig.  114),  which  is 
almost  wholly  made  up  of  the  spiral  shells  of  a  species  of 
Endothyra.  In  the  same  way,  though  to  a  less  extent  the 
black  Carboniferous  marbles  of  Ireland,  (and  the  similar  mar 
bles  of  Yorkshire,  the  limestones  of  the  west  of  England  and 
of  Derbyshire,  and  the  great  "  Scar  Limestones  "  of  the  north 
of  England,  contain  great  numbers  of  Foraminif  erous  shells ; 
whilst  similar  organisms  commonly  occur  in  the  shale-beds 
associated  with  the  limestones  throughout  the  Lower  Carbon- 
iferous series.  One  of  the  most  interesting  of  the  British  Car- 
boniferous forms  is  the  Sac- 
cammina  of  Mr.  Henry  Brady, 
which  is  sometimes  present  in 
considerable  numbers  in  the 
limestones  of  Northumberland, 
Cumberland,  and  the  west 
of  Scotland,  and  which  is  con- 
spicuous for  the  .comparatively 
large  size  of  its  spheroidal  or 
pear-shaped  shell  (reaching 
from  an  eighth  to  a  fifth  of  an 
inch  in  size).  More  widely  dis- 
tributed are  the  generally  spin- 
dle-shaped shells  of  Fusulina 
(fig.  115),  which  occur  in  vast 
numbers  in  the  Carboniferous 
Limestone  of  Russia,  Arme- 
nia, the  Southern  Alps,  and 
Spain,  similar  forms  occurring  in  equal  profusion  in  the  higher 


Fig.  114.— Transparent  slice  of  Carbon- 
iferous Limestone,  from  Spergen  Hill,  In- 
diana, U.  S.,  showing  numerous  shells  of 
Endothyra  (Rotalia),  Baileyl,  slightly  en- 
larged. (Original.) 


176  HISTORICAL  PALAEONTOLOGY. 

limestones  which  are  found  in  the  Coal-measures  of  the  United 

States,  in  Ohio,  Illinois, 
Indiana,  Missouri,  &c.  Mr. 
Henry  Brady,  lastly,  has 
shown  that  we  have  in  the 

Nummulina  pristina  of  the 
Fig.    115.  —  Fumllna    cylindnca.    Carbon-        ~     .        . ..  P 

iferous  Limestone,  Russia.  Carboniferous  Limestone  of 

Namur  a  genuine  Nummu- 

lite,  precursor  of   the   great   important   family   of   the   Tertiary 
Nummulites. 

The  sub-kingdom  of  the  Ccelenterates,  so  far  as  certainly 
known,  is  represented  only  by  Corals ;  *  but  the  remains  of 
these  are  so  abundant  in  many  of  the  limestones  of  the  Car- 
boniferous formation  as  to  constitute  a  feature  little  or  not  at 
all  less  conspicuous  than  that  afforded  by  the  Crinoids.  As  is 
the  case  in  the  preceding  period,  the  Corals  belong,  almost 
exclusively,  to  the  groups  of  the  Rugosa  and  Tabulata;  and 
there  is  a  general  and  striking  resemblance  and  relationship 
between  the  coral-fauna  of  the  Devonian  as  a  whole,  and  that 
of  the  Carboniferous.  Nevertheless,  there  is  an  equally  decided 
and  striking  amount  of  difference  between  these  successive 
faunas,  due  to  the  fact  that  the  great  majority  of  the  Carbon- 
iferous species  are  new ;  whilst  some  of  the  most  characteristic 
Devonian  genera  have  nearly  or  quite  disappeared,  and  several 
new  genera  now  make  their  appearance  for  the  first  time. 
Thus,  the  characteristic  Devonian  types  Heliophyllum,  Pachy- 
phyllum,  Chonophyllum,  Acervularia,  Spongophyllum,  Smithia, 
Endophyllum,  and  Cystiphyllum,  have  now  disappeared ;  and 
the  great  masses  of  Favosites  which  are  such  a  striking  feature 
in  the  Devonian  limestones,  are  represented  but  by  one  or  two 
degenerate  and  puny  successors.  On  the  other  hand,  we  meet 
in  the  Carboniferous  rocks  not  only  with  entirely  new  genera — 
such  as  Axophyllum,  Lophophyllum,  and  Londsdaleia — but  we 
have  an  enormous  expansion  of  certain  types  which  had  just 
begun  to  exist  in  the  preceding  period.  This  is  especially 
well  seen  in  the  case  of  the  genus  Lithostrotion  (fig.  116,  fc), 
which  more  than  any  other  may  be  considered  as  the  predom- 
inant Carboniferous  group  of  Corals.  All  the  species  of 
Lithostrotion  are  compound,  consisting  either  of  bundles  of 

*  A  singular  fossil  has  been  described  by  Professor  Martin  Duncan 
and  Mr.  Jenkins  from  the  Carboniferous  rocks  under  the  name  of  Palao- 
corvne,  and  has  been  referred  to  the  Hydroid  Zoophytes  (Corynida). 
Doubt,  however,  has  been  thrown  by  other  observers  on  the  correctness 
of  this  reference. 


THE  CARBONIFEROUS  PERIOD.  177 

loosely-approximated  cylindrical  stems,  or  of  similar  "  coral- 
lites  "  closely  aggregated  together  into  astraeiform  colonies,  and 
rendered  polygonal  by  mutual  pressure.  This  genus  has  a 
historical  interest,  as  having  been  noticed  as  early  as  in  the 
year  1699  by  Edward  Lhwyd;  and  it  is  geologically  important 
from  its  wide  distribution  in  the  Carboniferous  rocks  of  both 
the  Old  and  New  Worlds.  Many  species  are  known,  and  whole 
beds  of  limestone  are  often  found  to  be  composed  of  little  else 
than  the  skeletons  of  these  ancient  corals,  still  standing  upright 
as  they  grew.  Hardly  less  characteristic  of  the  Carboniferous 
than  the  above  is  the  great  group  of  simple  "cup-corals,"  of 
which  Clisiophyllum  is  the  central  type.  Amongst  types  which 
commenced  in  the  Silurian  and  Devonian,  but  which  are  still 
well  represented  here,  may  be  mentioned  Syringopora  (fig.  116, 
e),  with  its  colonies  of  delicate-  cylindrical  tubes  united  at  in- 
tervals by  cross-bars;  Zaphrentis  (fig.  116,  rf),  with  its  cup- 
shaped  skeleton  and  the  well-marked  depression  (or  "  fossula  ")• 
on  one  side  of  the  calice ;  Amplexus  (fig.  116,  c),  with  its 
cylindrical,  often  irregularly  swollen  coral  and  short  septa; 
Cyathophyllum  (fig.  116,  a),  sometimes  simple,  sometimes  form- 
ing great  masses  of  star-like  corallites ;  and  Chatetes,  with  its 
branched  stems,  and  its  minute,  "tabulate"  tubes  (fig.  116,  /). 
The  above,  together  with  other  and  hardly  less  characteristic 
forms,  combine  to  constitute  a  coral-fauna  which  is  not  only  in 
itself  perfectly  distinctive,  but  •  which  is  of  especial  interest, 
from  the  fact  that  almost  all  the  varied  types  of  which  it  is 
composed  disappeared  utterly  before  the  close  of  the  Carbon- 
iferous period.  In  the  first  marine  sediments  of  a  calcareous 
nature  which  succeeded  to  the  Coal-measures  (the  magnesian 
limestones  of  the  Permian),  the  great  group  of  the  Rugose 
corals,  which  flourished  so  largely  throughout  the  Silurian,  De- 
vonian, and  Carboniferous  periods,  is  found  to  have  all  but 
disappeared,  and  it  is  never  again  represented  save  sporadic- 
ally and  by  isolated  forms. 

Amongst  the  Echinoderms,  by  far  the  most  important  forms 
are  the  Sea-lilies  and  the  Sea-urchins — the  former  from  their 
great  abundance,  and  the  latter  from  their  singular  structure ; 
but  the  little  group  of  the  "  Pentremites "  also  requires  to  be 
noticed.  The  Sea-lilies  are  so  abundant  in  the  Carboniferous 
rocks,  that  it  has  been  proposed  to  call  the  earlier  portion  of 
the  period  the  "  Age  of  Crinoids."  Vast  masses  of  the  lime- 
stones of  the  period  are  "  crinoidal, "  being  more  or  less  ex- 
tensively composed  of  the  broken  columns,  and  detached  plates 


i;8  HISTORICAL  PALAEONTOLOGY. 

and  joints  of  Sea-lilies,  whilst  perfect  "heads"  may  be  exceed- 
ingly rare  and  difficult  to  procure.  In  North  America  the  re- 
mains of  Crinoids  are  even  more  abundant  at  this  horizon  than 


Fig.  116. — Corals  of  the  Carboniferous  Limestone,  a,  Cyathophyllumparacida,  show- 
ing young  corallites  budded  forth  from  the  disc  of  the  old  one  ;  a',  One  of  the  corallites 
of  the  same,  seen  in  cross-section  -,  b,  Fragment  of  a  mass  of  Lithostrotion  irregulare; 
&',  One  of  the  corallites  of  the  same,  divided  transversely  ;  c,  Portion  of  the  simple 
cylindrical  coral  of  Amplexus  coralloides;  c',  Transverse  section  of  the  same  species  ; 
d,  Zaphrentis  vermicularis,  showing  the  depression  or  "fossula"  on  one  side  of  the 
cup  ;  e,  Fragment  of  a  mass  of  Syringopora  ramulosa;  /.  Fragment  of  Chcetetes 
tumidus ;  f ,  Portion  of  the  surf  ace  of  the  same,  enlarged.  From  the  Carboniferous 
Limestone  of  Britain  and  Belgium.  (After  Thomson,  De  Koninck,  Milne-Edwards 
and  Haime,  and  the  Author.) 


in  Britain,  and  the  specimens  found  seem  to  be  commonly 
more  perfect.  The  commonest  of  the  Carboniferous  Crinoids 
belong  to  the  genera  Cyaihocrinus,  Actinocrinus,  Platycrinus, 


THE  CARBONIFEROUS  PERIOD.  179 

(fig.  117),  Poteriocrinus,  Zeacrinus,  and  Forbesiocrinus.  Closely 
allied  to  the  Crinoids,  or  forming  a  kind  of  transition  between 
these  and  the  Cystideans,  is  the  little  group  of  the  "  Pentre- 
mites, "  or  Blastoids,  (fig.  118).  This  group  is  first  known  to 
have  commenced  its  existence  in  the  Upper  Silurian,  and  it 
increased  considerably  in  numbers  in  the  Devonian;  but  it 
was  in  the  seas  of  the  Carboniferous  period  that  it  attained  its 
maximum,  and  no  certain  representative  of  the  family  has  been 
detected  in  any  later  deposits.  The  "  Pentremites "  resemble 
the  Crinoids  in  having  a  cup-shaped  body  (fig.  118,  A)  enclosed 
by  closely-fitting  calcareous  plates,  and  supported  on  a  short 
stem  or  "  column, "  composed  of  numerous  calcareous  pieces 
flexibly  articulated  together.  They  differ  from  the  Crinoids, 
however,  in  the  fact  that  the  upper  surface  of  the  body  does 
not  support  the  crown  of  branched  feathery  "  arms, "  which  are 
so  characteristic  of  the  latter.  On  the  contrary,  the  summit  of 
the  cup  is  closed  up  in  the  fashion  of  a  flower-bud,  whence  the 


Fig.  117.— Platycrinua  tricontadactylus,  Lower  Carboniferous.  The  left-hand 
figure  shows  the  calyx,  arms,  and  upper  |part  of  the  stem  ;  and  the  figure  next  this 
shows  the  surface  of  one  of  the  joints  of  the  column.  The  right-hand  figure  shows  the 
proboscis.  (After  M'Coy.) 

technical  name  of  Blastoidea  applied  to  the  group  (Gr.  blastos, 
a  bud;  eldos,  form).    From  the  top  of  the  cup  radiate  five  broad, 


i8o 


HISTORICAL  PALAEONTOLOGY. 


transversely-striated  areas  (fig.  118,  C),  each  with  a  longitudi- 
nal groove  down  its  middle ;  and  along  each  side  of  each  of 
these  grooves  there  seems  to  have  been  attached  a  row  of 
short  jointed  calcareous  filaments  or  "  pinnules.  " 


Fig.  118.— A,  Pentremites  pyriformia,  side- view  of  the  body  ("calyx  ");  The  same 
viewed  from  below,  showing  the  arrangement  of  the  plates  ;  C,  Body  of  Pentremites 
conoideus,  viewed  from  above.  Carboniferous. 

A  few  Star-fishes  and  Brittle-stars  are  known  to  occur  in  the 
Carboniferous  rocks;  but  the  only  other  Echinoderms  of  this 
period  which  need  be  noticed  are  the  Sea-urchins  (Echinoids). 
Detached  plates  and  spines  of  these  are  far  from  rare  in  the 
Carboniferous  deposits;  but  anything  like  perfect  specimens 
are  exceedingly  scarce.  The  Carboniferous-  Sea-urchins  agree 
with  those  of  the  present  day  in  having  the  body  enclosed  in 
a  shell,  formed  by  an  enormous  number  of  calcareous  plates 
articulated  together.  The  shell  may  be  regarded  as,  typically, 
nearly  spherical  in  shape,  with  the  mouth  in  the  center  of  the 
base,  and  the  excretory  opening  or  vent  at  the  summit.  In  both 
the  ancient  forms  and  the  recent  ones,  the  plates  of  the  shell 
are  arranged  in  ten  zones  which  generally  radiate  from  the 
summit  to  the  center  of  the  base.  In  five  of  these  zones — 
termed  the  "  ambulacral  areas " — the  plates  are  perforated  by 


THE  CARBONIFEROUS  PERIOD.  181 

minute  apertures  or  "  pores, "  through  which  the  animal  can 
protrude  the  little  water-tubes  ("tube-feet")  by  which  its  loco- 
motion is  carried  on.  In  the  other  five  zones — the  so-called 
"  inter-ambulacral  areas " — the  plates  are  of  larger  size,  and 
are  not  perforated  by  any  apertures.  In  all  the  modern  Sea- 
urchins  each  of  these  ten  zones,  whether  perforate  or  imper- 
forate,  is  composed  of  two  rows  of  plates;  and  there  are  thus 
twenty  rows  of  plates  in  all.  In  the  Palaeozoic  Sea-urchins,  on 
the  other  hand,  the  "  ambulacral  areas "  are  often  like  those 
of  recent  forms,  in  consisting  of  two  rows  of  perforated  plates 
(fig.  119);  but  the  "inter-ambulacral  areas"  are  always  quite 
peculiar  in  consisting  each  of  three,  four,  five,  or  more  rows  of 
large  imperforate  plates,  whilst  there  are  sometimes  four  or  ten 
rows  of  plates  in  the  "  ambulacral  areas "  also :  so  that  there 
are  many  more  than  twenty  rows  of  plates  in  the  entire  shell. 
Some  of  the  Palaeozoic  Sea-urchins,  also,  exhibit  a  very  pecu- 
liar singularity  of  structure  which  is  only  known  to  exist  in  a 


Fig.  119. — Palcecfiinut  ellipticus,  one  of  the  Carboniferous  Sea-urchins.  The  left- 
hand  figure  shows  one  of  the  "  ambulacral  areas  "  enlarged,  exhibiting  the  perforated 
plates.  The  right-hand  figure  exhibits  a  single  plate  from  one  of  the  "inter-ambu- 
lacral areas."  (After  M'Coy.) 


very  few  recently-discovered  modern  forms  (viz.,  Calveria  and 
Phormosoma).  The  plates  of  the  inter-ambulacral  areas, 
namely,  overlap  one  another  in  an  imbricating  manner,  so  as 
to  communicate  a  certain  amount  of  flexibility  to  the  shell ; 
whereas  in  the  ordinary  living  forms  these  plates  are  firmly 
articulated  together  by  their  edges,  and  the  shell  forms  a  rigid 
immovable  box.  The  Carboniferous  Sea-urchins  which  ex- 
hibit this  extraordinary  peculiarity  belong  to  the  genera  Lepi- 
dechinus  and  Lepidesthes,  and  it  seems  tolerably  certain  that 


182  HISTORICAL  PALAEONTOLOGY. 

a  similar  flexibility  of  the  shell  existed  to  a  less  degree  in 
the  much  more  abundant  genus  Archceocidaris.  The  Carbon- 
iferous Sea-urchins,  like  the  modern  ones,  possessed  movable 
spines  of  greater  or  less  length,  articulated  to  the  exterior  of 
the  shell;  and  these  structures  are  of  very  common  occur- 
rence in  a  detached  condition.  The  most  abundant  genera 
are  Archczocidaris  and  Palcechinus;  but  the  characteristic 
American  forms  belong  principally  to  Melonites,  Oligoporus, 
and  Lepidechinus. 

Amongst  the  Annelides  it  is  only  necessary  to  notice  the  little 
spiral    tubes    of    Spirorbis    Carbonarius    (fig.    120),    which    are 


Fig.  120.— Spirorbis  (Microconchus)  Carbonarius,  of  the  natural  size,  attached  to  a 
fossil  plant,  and  magnified.  Carboniferous,  Britain  and  North  America.  (After 
Dawson.) 


commonly  found  attached  to  the  leaves  or  stems  of  the  Coal- 
plants.  This  fact  shows  that  though  the  modern  species  of 
Spirorbis  are  inhabitants  of  the  sea,  these  old  representatives 
of  the  genus  must  have  been  capable  of  living  in  the  brackish 
waters  of  lagoons  and  estuaries. 

The  Crustaceans  of  the  Carboniferous  rocks  are  numerous, 
and  belong  partly  to  structural  types  with  which  we  are  already 
familar,  and  partly  to  higher  groups  which  come  into  existence 
here  for  the  first  time.  The  gigantic  Eurypterids  of  the  Upper 
Silurian  and  Devonian  are  but  feebly  represented,  and  make 
their  final  exit  here  from  the  scene  of  life.  Their  place,  how- 
ever, is  taken  by  peculiar  forme  belonging  to  the  allied  group 
of  the  Xiphosura,  represented  at  the  present  day  by  the  King- 
crabs  or  "Horse-shoe  Crabs"  (Limulus).  Characteristic  forms 
of  this  group  appear  in  the  Coal-measures  both  of  Europe  and 
America;  and  though  constituting  three  distinct  genera  (Prest- 
zvichia,  Belinurus,  and  Euproops),  they  are  all  nearly  related 
to  one  another.  The  best  known  of  them,  perhaps,  is  the 


THE  CARBONIFEROUS  PERIOD. 


183 


Fig.  121 .  —  Prestwichia  rotundata,  a  Llmuloid 
Crustacean.  Coal-measures,  Britain.  (After  Henry 
Woodward.) 


Prestwichia  rotundata  of  Coalbrookdale,  here  figured  (fig.  121). 
The  ancient  and  for- 
merly powerful  order 
of  the  Trilobites  also 
undergoes  its  final  ex- 
tinction here,  not  sur- 
viving the  deposition 
of  the  Carboniferous 
Limestone  series  in 
Europe,  but  extending 
its  range  in  America 
into  the  Coal-meas- 
ures. All  the  known 
Carboniferous  forms 
are  small  in  size  and 
degraded  in  point  of 
structure,  and  they 
are  referable  to  but 
three  genera  {Phil- 
lipsia,  GriffitJiides,  and 
Brachymetopus},  be- 
longing to  a  single  family.  The  Phillipsia  seminifera  here 
figured  (fig.  122,  a,)  is  a  characteristic  species  in  the  old  World. 
The  water-fleas  (Ostracoaa)  are  extremely  abundant  in  the 
Carboniferous  rocks,  whole  strata  being  often  made  up  of  little 
else  than  the  little  bivalved  shells  of  these  Crustaceans.  Many 
of  them  are  extremely  small,  averaging  about  the  size  of  a 
millet-seed ;  but  a  few  forms,  such  as  Entomoconchus  Scouleri 
(fig.  122,  <r),  may  attain  a  length  of  from  one  to  three  quarters 
of  an  inch.  The  old  group  of  the  Phyjllopods  is  likewise  still 
represented  in  some  abundance,  partly  by  tailed  forms  of  a 
shrimp-like  appearance,  such  as  Dithyrocaris  (fig.  122,  d),  and 
partly  by  the  curious  striated  Estherice  and  their  allies,  which 
present  a  curious  resemblance  to  the  true  Bivalve  Molluscs  (fig. 
122,  &).  Lastly,  we  meet  for  the  first  time  in  the  Carboniferous 
rocks  with  the  remains  of  the  highest  of  all  the  groups  of 
Crustaceans — namely,  the  so-called  "  Decapods, "  in  which  there 
are  five  pairs  of  walking-limbs,  and  the  hinder  end  of  the  body 
("abdomen")  is  composed  of  separate  rings,  whilst  the  anterior 
end  is  covered  by  a  head-shield  or  "  carapace. "  All  the  Carbon- 
iferous Decapods  hitherto  discovered  resemble  the  existing 
Lobsters,  Prawns,  and  Shrimps  (the  Macrura),  in  having  a  long 
and  well-developed  abdomen  terminated  by  an  expanded  tail-fin. 


i84 


HISTORICAL  PALEONTOLOGY. 


The  Palaocaris  typus  (fig.  122,  e}  and  the  Anthrapalamon  gracilis 
(fig.  122,  /),  from  the  Coal-measures  of  Illinois,  are  two  of  the 
best  understood  and  most  perfectly  preserved  of  the  few  known 
representatives  of  the  "  Long-tailed "  Decapods  in  the  Car- 
boniferous series.  The  group  of  the  Crabs  or  "  Short-tailed " 
Decapods  (Brachyura),  in  which  the  abdomen  is  short,  not 
terminated  by  a  tail-fin,  and  tucked  away  out  of  sight  beneath 
the  body,  is  at  present  not  known  to  be  represented  at  all  in 
the  Carboniferous  deposits. 

In  addition  to  the  water-inhabiting  group  of  the  Crustaceans, 
we   find  the   articulate   animals   to   be   represented   by   members 


Fig.  122. — Crustaceans  of  the  Carboniferous  Rocks,  a,  Philllpsia  seminifera,  of  the 
natural  size— Mountain  Limestone,  Europe  ;  6,  One  valve  of  the  shell  of  Estfieria 
tenella,  of  the  natural  size  and  enlarged — Coal-measures.  Europe  ;  c,  Bivalved  shell  of 
Entonwconchu*  Scoulert,  of  the  natural  size— Mountain  Limestone,  Europe  ;d,  Dlthyro- 
caris  Scouleri,  reduced  in  size— Mountain  Limestone,  Ireland  ;  e,  Palceocaris  typus, 
slightly  enlarged— Coal-measures,  North  America ;  /,  Anthrapalcemon  gracAlis,  of 
the  natural  size— Coal-measures,  North  America.  (After  De  Koninck,  M'Coy,  Rupert 
Jones,  a«d  Meek  and  Worthen.) 

belonging  to  the  air-breathing  classes  of  the  Arachnida,  Myria- 
poda,  and  Insecta.  The  remains  of  these,  as  might  have  been 
expected,  are  not  known  to  occur  in  the  marine  limestones  of 
the  Carboniferous  series,  but  are  exclusively  found  in  beds  asso- 


THE  CARBONIFEROUS  PERIOD.  185 

ciated  with  the  Coal,  which  have  been  deposited  in  lagoons, 
estuaries,  or  marshes,  in  the  immediate  vicinity  of  the  land,  and 
which  actually  represent  an  old  land-surface.  The  Arachnids 
are  at  present  the  oldest  known  of  their  class,  and  are  repre- 
sented both  by  true  Spiders  and  Scorpions.  Remains  of  the 
latter  (fig.  123)  have  been  found  both  in  the  Old  and  New 
Worlds,  and  indicate  the  existence  in  the  Carboniferous  period 
of  Scorpions  differing  but  very  little  from  existing  forms.  The 
group  of  the  Myriapoda,  including  the  recent  Centipedes  and 
Galley-worms,  is  likewise  represented  in  the  Carboniferous  strata, 
but  by  forms  in  many  respects  very  unlike  any  that  are  known 
to  exist  at  the  present  day.  The  most  interesting  of  these 
were  obtained  by  Principal  Dawson,  along  with  the  bones  of 
Amphibians  and  the  shells  of  Land-snails,  in  the  sediment  filling 
the  hollow  trunks  of  Sigillaria,  and  they  belong  to  the  genera 


Fig.  123.— Cyclophthalmus  senior.    A  fossil  Scorpion  from  the  Coal-ineasures 
of  Bohemia. 

Xylobius  (fig.  124)  and  Archiulus.  Lastly,  the  true  insects  are 
represented  by  various  forms  of  Beetles  (Coleoptera},Orthoptera 
(such  as  Cockroaches),  and  Neur apterous  insects  resembling 
those  which  we  have  seen  to  have  existed  towards  the  close  of 
the  Devonian  period.  One  of  the  most  remarkable  of  the 


186 


HISTORICAL  PALAEONTOLOGY. 


latter  is  a  huge  May-fly  (Haplophlebium  Barnesi,  fig.  125),  with 
netted  wings  attaining  an  expanse  of  fully  seven  inches,  and 
therefore  much  exceeding  any  existing  Ephemerid  in  point 
of  size. 

The  lower  groups  of  the  Mollusca  are  abundantly  represented 


Fig.  124.— Xylobiiis  Sigillarice,  a  Carboniferous  Myriapod.  a,  A  specimen,  of  the 
natural  size  ;  6,  Anterior  portion  of  the  same,  enlarged  ;  c.  Posterior  portion,  enlarged. 
From  the  Coal-uieasures  of  Nova  Scotia.  (After  Dawson.) 

in  the  marine  strata  of  the  Carboniferous  series  by  Polyzoans 
and  Brachiopods.     Amongst  the  former,  although  a  variety  of 


Fig.  125.—ffaplophlebium  Barnesi,  a  Carboniferous  insect,  from  the  Coal-measures 
of  Nova  Scotia.     (After  Dawson.) 

other  types  are  known,  the  majority  still  belong  to  the  old 
group  of  the  "Lace-corals"  (Fenestellida),  some  of  the  charac- 
teristic forms  of  which  are  here  figured  (fig.  126).  The  graceful 
netted  fronds  of  Fenestella,  Retepora,  and  Polypora(fig.  126  a) 


THE  CARBONIFEROUS  PERIOD. 


187 


are  highly  characteristic,  as  are  the  slender  toothed  branches 
of  Glauconome  (fig.  126,  b).  A  more  singular  form,  however,  is 
the  curious  Archimedes  (fig.  126,  c),  which  is  so  characteristic 
of  the  Carboniferous  formation  of  North  America.  In  this  re- 
markable type,  the  colony  consists  of  a  succession  of  funnel- 


Fig.  126.— Carboniferous  Polyzoa.  a,  Fragment  of  Polypora  dendroidea,  of  the 
natural  size,  Ireland  ;  a'  Small  portion  of  the  same,  enlarged  to  show  the  cells  ;  6, 
Glauconome  pulcherrima,  a  fragment,  of  the  natural  size,  Ireland  ;  V,  Portion  of  the 
same,  enlarged  ;  c,  The  central  screw-like  axis  of  Archimedes  Wortheni,  of  the  natural 
size — Carboniferous,  America  ;  c',  Portion  of  the  exterior  of  the ,  frond  of  the  same, 
enlarged  ;  c".  Portion  of  the  interior  of  the  frond  of  the  same  showing  the  mouths  of 
the  cells,  enlarged.  (After  M'Coy  and  Hall. ) 


shaped  fronds,  essentially  similar  to  Fenestella  in  their  structure, 
springing  in  a  continuous  spiral  from  a  strong  screw-like  vertical 
axis.  The  outside  of  the  fronds  is  simply  striated ;  but  the 
branches  exhibit  on  the  interior  the  mouths  of  the  little  cells 


i88  HISTORICAL  PALEONTOLOGY. 

in    which    the    semi-independent    beings    composing    the    colony 
originally  lived. 

The  Brachiopods  are  extremely  abundant,  and  for  the  most 
part  belong  to  types  which  are  exclusively  or  principally 
Palaeozoic  in  their  range.  The  old  genera  Strophomena,  Orthis 
(fig.  127,  c~),  Athyris  (fig.  127,  e),  Rhynchonella  (fig.  127,  g),  and 
Spirifera  (fig.  127,  /?),  are  still  well  represented — the  latter,  in 
particular,  existing  under  numerous  specific  forms,  conspicuous 
by  their  abundance  and  sometimes  by  their  size.  Along  with 
these  ancient  groups,  we  have  representatives — for  the  first  time 
in  any  plenty — of  the  great  genus  Terebratula  (fig.  127,  d), 
which  underwent  a  great  expansion  during  later  periods,  and 
still  exists  at  the  present  day.  The  most  characteristic  Car- 
boniferous Brachiopods,  however,  belong  to  the  family  of  the 
Productida,  of  which  the  principal  genus  is  Producta  itself. 
This  family  commenced  its  existence  in  the  Upper  Silurian 
with  the  genus  Chonetes,  distinguished  by  its  spinose  hinge- 
margin.  This  genus  lived  through  the  Devonian,  and  flourished 
in  the  Carboniferous  (fig.  127,  /).  The  genus  Producta  itself, 
represented  in  the  Devonian  by  the  nearly  allied  Productella, 
appeared  first  in  the  Carboniferous,  at  any  rate  in  force,  and 
survived  into  the  Permian ;  but  no  member  of  this  extensive 
family  has  yet  been  shown  to  have  over-lived  the  Palaeozoic 
period.  The  Producta  of  the  Carboniferous  are  not  only  ex- 
ceedingly abundant,  but  they  have  in  many  instances  a  most 
extensive  geographical  range,  and  some  species  attain  what 
may  fairly  be  considered  gigantic  dimensions.  The  shell  (fig. 
127,  a  and  b}  is  generally  more  or  less  semicircular,  with  a 
straight  hinge-margin,  and  having  its  lateral  angles  produced 
into  larger  or  smaller  ears  (hence  its  generic  name — "  cochlea 
producta").  One  valve  (the  ventral)  is  usually  strongly  convex, 
whilst  the  other  (the  dorsal)  is  flat  or  concave,  the  surface  of 
both  being  adorned  with  radiating  ribs,  and  with  hollow 
tubular  spines,  often  of  great  length.  The  valves  are  not 
locked  together  by  teeth,  and  there  is  no  sign  in  the  fully- 
grown  shell  of  an  opening  in  or  between  the  valves  for  the 
emission  of  a  muscular  stalk  for  the  attachment  of  the  shell  to 
foreign  objects.  It  is  probable,  therefore,  that  the  Producta, 
unlike  the  ordinary  Lamp-shells,  lived  an  independent  exist- 
ence, their  long  spines  apparently  serving  to  anchor  them 
firmly  in  the  mud  or  ooze  of  the  sea-bottom;  but  Mr.  Robert 
Etheridge,  jun.,  has  recently  shown  that  in  one  species  the 
spines  were  actually  employed  as  organs  of  adhesion,  whereby 


THE  CARBONIFEROUS  PERIOD. 


189 


the  shell  was  permanently  attached  to  some  extraneous  object, 
such  as  the  stem  of  a  Crinoid.  The  two  species  here  figured 
are  interesting  for  their  extraordinarily  extensive  geographical 
range — Producta  semireticulata  (fig.  127,  o)  being  found  in  the 
Carboniferous  rocks  of  Britain,  the  continent  of  Europe, 
Central  Asia,  China,  India,  Australia,  Spitsbergen,  and  North 
and  South  America;  whilst  P.  longispina  (fig.  127,  b)  has  a 
distribution  little  if  at  all  less  wide. 


Fig.  127  —Carboniferous  BracMopoda  a,  Producta  semiretic-ulala,  showing  th* 
slightly  concave  dorsal  valve ;  a'  Side  view  of  the  same,  showing  the  convex  ventral  valve ; 
b,  Producta  longispina,  c,  Orthia  resupinata  ;  d,  Terebratula  fiattata;  e,  Athyria  subtil- 
ita;  /,  Cho?ietf8  Harclre nuts ,  g,  Rhynchonellapleurodon;  h,  Spirtfera  trigonalia.  Most 
of  these  forms  are  widely  distributed  in  the  Carboniferous  Limestone  of  Britain,Europe, 
America,  &c.  All  the  figures  are  of  the  natural  size.  (After  Davidson,  De  Koninck,  and 
Meek.) 


The  higher  Mollusca  are  abundantly  represented  in  the 
Carboniferous  rocks  by  Bivalves  (Lamellibranchs),  Univalves 
(Gasteropoda),  Winged-snails  (Pteropoda),  and  Cephalopods. 
Amongst  the  Bivalves  we  may  note  the  great  abundance  of 


HISTORICAL  PALEONTOLOGY. 


Scallops  (Aviculopecten  and  other  allied  forms),  together  with 
numerous  other  types — some  of  ancient  origin,  others  repre- 
sented here  for  the  first  time.  Amongst  the  Gasteropods,  we 
find  the  characteristically  Palaeozoic  genera  Macrocheilus  and 
Loxonema,  the  almost  exclusively  Palaeozoic  Euomphalus,  and 
the  persistent  genus  Pleurotomaria;  whilst  the  free-swimming 
Univalves  (Heteropoda)  are  represented  by  Bellerophon  and  Por- 
cellia,  and  the  Pteropoda  by  the  old  genus  Conularia.  With  regard 
to  the  Carboniferous  Univalves,  it  is  also  of  interest  to  note  here 
the  first  appearance  of  true  air-breathing  or  terrestrial  Molluscs, 
as  discovered  by  Dawson  and  Bradley  in  the  Coal-measures  of 
Nova  Scotia  and  Illinois.  Some  of  these  (Conulus  priscus)  are 
true  Land-snails,  resembling  the  existing  Zonites;  whilst  others 
(Pupa  vetusta,  fig.  128)  appear  to  be  generically  inseparable 
from  the  "  Chrysalis-shells " 
(Pupa)  of  the  present  day. 
All  the  known  forms — three 
in  number — are  of  small  size, 
and  appear  to  have  been  local 
in  their  distribution  or  in  their 
preservation.  More  import- 
ant, however,  than  any  of  the 
preceding,  are  the  Cephalo- 
poda, represented,  as  before, 
exclusively  by  the  chambered 
shells  of  the  Tetrabranchiates. 
The  older  and  simpler  type  of 
these,  with  simple  plain  septa, 
and  mostly  a  central  siphuncle, 
is  represented  by  the  straight 
conical  shells  of  the  ancient 
genus  Orthoceras,  and  the  bow- 
shaped  shells  of  the  equally 
ancient  Cyrtoceras — some  of 
the  former  attaining  a  great  size. 
The  spirally-curved  discoidal 

shells  of  the  persistent  genus  Nautilus  are  also  not  unknown, 
and  some  of  these  likewise  exhibit  very  considerable  dimen- 
sions. Lastly,  the  more  complex  family  of  the  Ammonitida, 
with  lobed  or  angulated  septa,  and  a  dorsally-placed  siphuncle 
(situated  on  the  convex  side  of  the  curved  shells),  now  for  the 
first  time  commences  to  acquire  a  considerable  prominence. 
The  principal  representative  of  this  group  is  the  genus  Gonia- 


Flg.  128.— Pupa  (Dendropupa)  vetusta, 
a  Carboniferous  Land-snail  from  theCoal- 
measures  of  Nova  Scotia,  a,  The  shell,  of 
the  natural  size  ;  6,  The  same,  magnified; 
c,  Apex  of  the  shell,  enlarged  ;  d,  Portion 
of  the  surface,  enlarged.  (Alter  Dawson.) 


THE  CARBONIFEROUS  PERIOD. 


191 


tites  (fig.  129),  which  commenced  its  existence  in  the  Upper 
Silurian,  is  well  represented  in  the  De- 
vonian, and  attains  its  maximum  here. 
In  this  genus,  the  shell  is  spirally 
curved,  the  septa  are  strongly  lobed 
or  angulated,  though  not  elaborately 
frilled  as  in  the  Ammonites,  and  the 
siphuncle  is  dorsal.  In  addition  to 
Goniatites,  the  shells  of  true  Ammon- 
ites, so  characteristic  of  the  Secondary 
period,  have  been  described  by  Dr. 
Waagen  as  occurring  in  the  Carbon- 
iferous rocks  of  India. 


Fig.  129.— Gonlatitet  (Aganides)  Jossce.    Carboniferous  Limestone. 

Coming  finally  to  the  Vertcbrata,  we  have  in  the  first  place 
to  very  briefly  consider  the  Carboniferous  fishes.  These  are 
numerous;  but,  with  the  exception  of  the  still  dubious  "  Cono- 
donts, "  belong  wholly  to  the  groups  of  the  Ganoids  and  the 
Placoids  (including  under  the  former  head  remains  which  per- 
haps are  truly  referable  to  the  group  of  the  Dipnoi  or  Mud- 
fishes). Amongst  the  Ganoids,  the  singular  buckler-headed 
fishes  of  the  Upper  Silurian  and  Devonian  (Cephalaspida)  have 
apparently  disappeared;  and  the  principal  types  of  the  Car- 
boniferous belong  to  the  groups  respectively  represented  at 
the  present  day  by  the  Gar  pike  (Lepidosteus}  of  the  North 
American  lakes,  and  the  Polypterus  of  the  rivers  of  Africa.  Of 


192 


HISTORICAL  PALEONTOLOGY. 


the  former,  the  genera  Pal&oniscus  and  Amblypterus  (fig.  130), 
with  their  small  rhomboidal  and  enamelled  scales,  and  their 
strongly  unsymmetrical  tails,  are  perhaps  the  most  abundant. 
Of  the  latter,  the  most  important  are  species  belonging  to 


Fig.  130. — Amblypterua  macropterus.    Carboniferous. 


the  genera  Megalichthys  and  Rhizodus,  comprising  large  fishes, 
with  rhomboidal  scales,  unsymmetrical  .("  heterocercal ")  tails, 
and  powerful  conical  teeth.  These  fishes  are  sometimes  said 
to  be  "  sauroid, "  from  their  presenting  some  Reptilian  features 
in  their  organization,  and  they  must  have  been  the  scourges 
of  the  Carboniferous  seas.  The  remains  of  Placoid  fishes  in 
the  Carboniferous  strata  are  very  numerous,  but  consist  wholly 
of  teeth  and  fin-spines,  referable  to  forms  more  or  less  closely 
allied  to  our  existing  Port  Jackson  Sharks,  Dog-fishes,  and 
Rays.  The  teeth  are  of  very  various  shapes  and  sizes, — some 
with  sharp,  cutting  edges  (Petalodus,  Cladodus,  &c.)  ;  others  in 
the  form  of  broad  crushing  plates,  adapted,  like  the  teeth  of  the 
existing  Port  Jackson  Shark  (Cestracion  Philip  pi),  for  breaking 
down  the  hard  shells  of  Molluscs  and  Crustaceans.  Amongst 
the  many  kinds  of  these  latter,  the  teeth  of  Psammodus  and 
Cochliodus  (fig.  131)  may  be  mentioned  as  specially  charac- 
teristic. The  fin-spines  are  mostly  similar  to  those  so  common 
in  the  Devonian  deposits,  consisting  of  hollow  defensive  spines 
implanted  in  front  of  the  pectoral  or  other  fins,  usually  slightly 
curved,  often  superficially  ribbed  or  sculptured,  and  not  un- 
commonly serrated  or  toothed.  The  genera  Ctenacanthus, 
Gyracanthus,  Homacanthus,  &c.,  have  been  founded  for  the 
reception  of  these  defensive  weapons,  some  of  which  indicate 
fishes  of  great  size  and  predaceous  habits. 

In  the  Devonian  rocks  we  meet  with  no  other  remains  of 


THE  CARBONIFEROUS  PERIOD.  193 

Vertebrated  animals  save  fishes  only;  but  the  Carboniferous 
deposits  have  yielded  re- 
mains of  the  higher  group 
of  the  Amphibians.  This 
class,  comprising  our  ex- 
isting Frogs,  Toads,  and 
Newts,  stands  to  some  ex- 
tent in  a  position  midway 
between  the  class  of  the 
fishes-  and  that  of  the  true 
reptiles,  being  distinguished 
from  the  latter  by  the  fact  mg  131  .-Teeth  of  CochUodw,  contort™. 
that  its  members  invariably  Carboniferous  Limestone,  Britain, 

possess  gills   in  their  early 

condition,  if  not  throughout  life;  whilst  they  are  separated  from 
the  former  by  always  possessing  true  lungs  when  adult,  and 
by  the  fact  that  the  limbs  (when  present  at  all)  are  never  in 
the  form  of  fins.  The  Amphibians,  therefore,  are  all  water- 
breathers  when  young,  and  have  respiratory  organs  adapted 
for  an  aquatic  mode  of  life;  whereas,  when  grown  up,  they 
develop  lungs,  and  with  these  the  capacity  for  breathing  air 
directly.  Some  of  them,  like  the  Frogs  and  Newts,  lose  their 
gills  altogether  on  attaining  the  adult  condition ;  but  others, 
such  as  the  living  Proteus  and  Menobranchus,  retain  their  gills 
even  after  acquiring  their  lungs,  and  are  thus  fitted  indiffer- 
ently for  an  aquatic  or  terrestrial  existence.  The  name  of 
"  Amphibia, "  though  applied  to  the  whole  class,  is  thus  not 
precisely  appropriate  except  to  these  last-mentioned  forms 
(Gr.  amphi,  both;  bios,  life).  The  Amphibians  also  differ 
amongst  themselves  according  as  to  whether  they  keep  per- 
manently the  long  tail  which  they  all  possess  when  young  (as 
do  the  Newts  and  Salamanders),  or  lose  this  appendage  when 
grown  up  (as  do  the  Frogs  and  Toads).  Most  of  them  have 
naked  skins,  but  a  few  living  and  many  extinct  forms  have 
hard  structures  in  the  shape  of  scales  developed  in  the  integu- 
ment. All  of  them  have  well-ossified  skeletons,  though  some 
fossil  types  are  partially  deficient  in  this  respect;  and  all  of 
them  which  possess  limbs  at  all  have  these  appendages  sup- 
ported by  bones  essentially  similar  to  those  found  in  the  limbs 
of  the  higher  Vertebrates.  All  the  Carboniferous  Amphibians 
belong  to  a  group  which  has  now  wholly  passed  away — namely, 
that  of  the  Labyrinthodonts.  In  the  marine  strata  which  form 
the  base  of  the  Carboniferous  series  these  creatures  have  only 
13 


194 


HISTORICAL  PALEONTOLOGY. 


been  recognized  by  their  curious  hand-shaped  footprints,  similar 
in  character  to  those  which  occur  in  the  Triassic  rocks,  and  which 
will  be  subsequently  spoken  of  under  the  name  of  Cheirotherium. 
In  the  Coal-measures  of  Britain,  the  continent  of  Europe,  and 
North  America,  however,  many  bones  of  these  animals  have 
been  found,  and  we  are  now  tolerably  well  acquainted  with  a 
considerable  number  of  forms.  All  of  them  seem  to  have  be- 
longed to  the  division  of  Amphibians  in  which  the  long  tail 
of  the  young  is  permanently  retained;  and  there  is  evidence 
that  some  of  them  kept  the  gills  also  throughout  life.  The 
skull  is  of  the  characteristic  Amphibian  type  (fig.  132,  a),  with 
two  occipital  condyles,  and  having  its  surface  singularly  pitted 
and  sculptured;  and  the  vertebrae  are  hollowed  out  at  both 
ends.  The  lower  surface  of  the  body  was  defended  by  an 
armor  of  singular  integumentary  shields  or  scales  (fig.  132,  c)  ; 
and  an  extremely  characteristic  feature  (from  which  the  entire 


Pig.  132.— a,  Upper  surf  ace  of  the  skull  of  Anthracoaaurus  RvAselU,  one-sixth  of  the 
natural  size  ;  6,  Part  of  one  of  the  teeth  cut  across,  and  highly  magnified  to  show  the 
characteristic  labyrinthine  structure  ;  c,  One  of  the  integumentary  shields  or  scales, 
one-half  of  the  natural  size.  Coal-measures,  Northumberland.  (After  Atthey.) 

group  derives  its  name)  is,  that  the  walls  of  the  teeth  are  deeply 
folded,  so  as  to  give  rise  to  an  extraordinary  "  labyrinthine " 
pattern  when  they  are  cut  across  (fig.  132,  b).  Many  of  the 


THE  CARBONIFEROUS  PERIOD.  195 

Carboniferous  Labyrinthodonts  are  of  no  great  size,  some  of 
them  very  small,  but  others  attain  comparatively  gigantic 
dimensions,  though  all  fall  short  in  this  respect  of  the  huge 
examples  of  this  group  which  occur  in  the  Trias.  One  of  the 
largest,  and  at  the  same  time  most  characteristic,  forms  of  the 
Carboniferous  series,  is  the  genus  Anthracosaurus,  the  skull  of 
which  is  here  figured. 

No  remains  of  the  true  Reptiles,  Birds,  or  Quadrupeds  have 
as  yet  been  certainly  detected  in  the  Carboniferous  deposits  in 
any  part  of  the  world.  It  should,  however,  be  mentioned, 
that  Professor  Marsh,  one  of  the  highest  authorities  on  the 
subject,  has  described  from  the  Coal-formation  of  Nova  Scotia 
certain  vertebrae  which  he  believes  to  have  belonged  to  a 
marine  reptile  (Eosaurus  Acadianus},  allied  to  the  great 
Ichthyosauri  of  the  Lias.  Up  to  this  time  no  confirmation 
of  this  determination  has  been  obtained  by  the  discovery  of 
other  and  more  unquestionable  remains,  and  it  therefore  remains 
doubtful  whether  these  bones  of  Eosaurus  may  not  really  belong 
to  large  Labyrinthodonts. 

LITERATURE. 

The  following  list  contains  some  of  the  more  important  of  the 
original  sources  of  information  to  which  the  student  of  Carbonif- 
erous rocks  and  fossils  may  refer : — 

(1)  'Geology  of  Yorkshire,'  vol.  ii. ;   'The   Mountain   Lime- 

stone District. '    John  Phillips. 

(2)  '  Siluria. '  Sir  Roderick  Murchison. 

(3)  '  Memoirs  of  the  Geological  Survey  of  Great  Britain  and 

Ireland. ' 

(4)  '  Geological  Report  on  Londonderry, '  &c.     Portlock. 

(5)  '  Acadian  Geology. '    Dawson. 

(6)  '  Geology  of  Iowa. '  vol.  i.  James  Hall. 

(7)  'Reports  of  the  Geological  Survey  of  Illinois'   (Geology 

and  Palaeontology).     Meek,  Worthen,  &c. 

(8)  'Reports   of    the   Geological    Survey   of    Ohio'    (Geology 

and  Palaeontology).     Newberry,  Cope,  Meek,  Hall,  &c. 

(9)  *  Description  des  Animaux  fossiles  qui  se  trouvent  dans  le 

Terrain  Carbonif  ere  de  la  Belgique, '  1843 ;  with  sub- 
sequent monographs  on  the  genera  Prnductus  and 
Chonetcs,  on  Crinoids,  on  Corals,  &c.  De  Koninck. 

(10)  'Synopsis    of    the    Carboniferous    Fossils    of    Ireland.' 

M'Coy. 
(n)  'British  Palaeozoic  Fossils.'  M'Coy. 

(12)  'Figures  of  Characteristic  British  Fossils.'     Baily. 

(13)  'Catalogue  of  British  Fossils.'     Morris. 

(14)  '  Monograph  of  the  Carboniferous  Brachiopoda  of  Britain 

(Palaeontographical  Society).     Davidson. 

(15)  'Monograph     of     the     British     Carboniferous     Corals' 

Palaeontographical  Society).  Milne-Edwards  and  Haime. 


196  HISTORICAL  PALEONTOLOGY. 

(16)  'Monograph    of    the    Carboniferous    Bivalve    Entomos- 

traca  of  Britain'     ( Palseontographical  Society).    Rupert 
Jones,  Kirkby,  and  George  S.  Brady. 

(17)  '  Monograph     of     the     Carboniferous     Foraminifera     of 

Britain'   (Palseontographical  Society).     H.  B.  Brady. 

(18)  "On  the  Carboniferous  Fossils  of  the  West  of  Scotland" 
— '  Trans.  Geol.  Soc., '  of  Glasgow,  vol.  iii.,  Supplement. 
Young  and  Armstrong. 

(19)  '  Poissons  Fossiles. '  Agassiz. 

(20)  "  Report    on    the    Labyrinthodonts    of    the    Coal-meas- 

ures " — '  British  Association  Report, '  1873.     L.  C.  Miall. 

(21)  'Introduction  to  the  Study  of  Palaeontological  Botany.' 

John  Hutton  Balfour. 

(22)  '  Traite  de  Paleontologie  Vegetale. '     Schimper. 

(23)  '  Fossil  Flora. '    Lindley  and  Hutton. 

(24)  '  Histoire  des  Vegetaux  Fossiles. '     Brongniart. 

(25)  'On    Calamites    and    Calamodendron '    (Monographs    of 

the  Palaeontographical  Society).    Binney. 

(26)  '  On  the  Structure  of  Fossil  Plants  found  in  the  Carbonif- 

erous Strata '  (Palseontographical  Society).  Binney. 
Also  numerous  memoirs  by  Huxley,  Davidson,  Martin  Duncan, 
Professor  Young,  John  Young,  R.  Etheridge,  jun. ;  Baily,  Car- 
ruthers,  Dawson,  Binney,  Williamson,  Hooker,  Jukes,  Geikie, 
Rupert  Jones,  Salter,  and  many  other  British  and  Foreign 
observers.  

CHAPTER  XIV. 

THE  PERMIAN  PERIOD. 

The  Permian  formation  closes  the  long  series  of  the  Palaeo- 
zoic deposits,  and  may  in  some  respects  be  considered  as  a 
kind  of  appendix  to  the  Carboniferous  system,  to  which  it  can- 
not be  compared  in  importance,  either  as  regards  the  actual 
bulk  of  its  sediments  or  the  interest  and  variety  of  its  life- 
record.  Consisting,  as  it  does,  largely  of  red  rocks — sand- 
stones and  marls — for  the  most  part  singularly  destitute  of 
organic  remains,  the  Permian  rocks  have  been  regarded  as  a 
lacustrine  or  fluviatile  deposit;  but  the  presence  of  well-devel- 
oped limestones  with  indubitable  marine  remains  entirely 
negatives  this  view.  It  is,  however,  not  improbable  that  we 
are  presented  in  the  Permian  formation,  as  known  to  us  at 
present,  with  a  series  of  sediments  laid  down  in  inland  seas  of 
great  extent,  due  to  the  subsidence  over  large  areas  of  the 
vast  land-surfaces  of  the  Coal-measures.  This  view,  at  any 
rate,  would  explain  some  of  the  more  puzzling  physical  char- 
acters of  the  formation,  and  would  not  be  definitely  negatived 
by  any  of  its  fossils. 

A  large  portion  of  the  Permian  series,  as  already  remarked, 


THE  PERMIAN  PERIOD.  197 

consists  of  sandstones  and  marls,  deeply  reddened  by  peroxide 
of  iron,  and  often  accompanied  by  beds  of  gypsum  or  deposits 
of  salt.  In  strata  of  this  nature  few  or  no  fossils  are  found; 
but  their  shallow-water  origin  is  sufficiently  proved  by  the 
presence  of  the  footprints  of  terrestrial  animals,  accompanied 
in  some  cases  by  well-defined  "  ripple-marks. "  Along  with 
these  are  occasionally  found  massive  breccias,  holding  larger 
or  smaller  blocks  derived  from  the  older  formations;  and  these 
have  been  supposed  to  represent  an  old  "  boulder-clay, "  and 
thus  to  indicate  the  prevalence  of  an  arctic  climate.  Beds  of 
this  nature  must  also  have  been  deposited  in  shallow  water. 
In  all  regions,  however,  where  the  Permian  formation  is  well 
developed,  one  of  its  most  characteristic  members  is  a  Mag- 
nesian  limestone,  often  highly  and  fantastically  concretionary, 
but  containing  numerous  remains  of  genuine  marine  animals, 
and  clearly  indicating  that  it  was  deposited  beneath  a  mod- 
erate depth  of  salt  water. 

It  is  not  necessary  to  consider  here  whether  this  formation 
can  be  retained  as  a  distinct  division  of  the  geological  series. 
The  name  of  Permian  was  given  to  it  by  Sir  Roderick  Murchi- 
son,  from  the  province  of  Perm  in  Russia,  where  rocks  of  this 
age  are  extensively  developed.  Formerly  these  rocks  were 
grouped  with  the  succeeding  formation  of  the  Trias  under  the 
common  name  of  "  New  Red  Sandstone. "  This  name  was 
given  them  because  they  contain  a  good  deal  of  red  sandstone, 
and  because  they  are  superior  to  the  Carboniferous  rocks, 
while  the  Old  Red  Sandstone  is  inferior.  Nowadays,  how- 
ever, the  term  "  New  Red  Sandstone "  is  rarely  employed, 
unless  it  be  for  red  sandstones  and  associated  rocks,  which 
are  seen  to  overlie  the  Coal-measures,  but  which  contain  no 
fossils  by  which  their  exact  age  may  be  made  out.  Under 
these  circumstances,  it  is  sometimes  convenient  to  employ  the 
term  "  New  Red  Sandstone. "  The  New  Red,  however,  of  the 
older  geologists,  is  now  broken  up  into  the  two  formations  of 
the  Permian  and  Triassic  rocks — the  former  being  usually  con- 
sidered as  the  ,top  of  the  Palaeozoic  series,  and  the  latter  con- 
stituting the  base  of  the  Mesozoic. 

In  many  instances,  the  Permian  rocks  are  seen  to  repose 
unconformably  upon  the  underlying  Carboniferous,  from  which 
they  can  in  addition  be  readily  separated  by  their  lithological 
characters.  In  other  instances,  however,  the  Coal-measures 
terminate  upwards  in  red  rocks,  not  distinguishable  by  their 
mineral  characters  from  Permian;  and  in  other  cases  no 


198  HISTORICAL  PALAEONTOLOGY. 

physical  discordance  between  the  Carboniferous  and  Per- 
mian strata  can  be  detected.  As  a  general  rule,  also,  the 
Permian  rocks  appear  to  pass  upwards  conformably  into  the 
Trias.  The  division,  therefore,  between  the  Permian  and  Tri- 
assic  rocks,  and  consequently  between  the  Palaeozoic  and  Me- 
sozoic  series,  is  not  founded  upon  any  conspicuous  or  universal 
physical  break,  but  upon  the  difference  in  life  which  is  ob- 
served in  comparing  the  marine  animals  of  the  Carboniferous 
and  Permian  with  those  of  the  Trias.  It  is  to  be  observed,  how- 
ever, that  this  difference  can  be  solely  due  to  the  fact  that  the 
Magnesian  Limestone  of  the  Permian  series  presents  us  with 
only  a  small,  and  not  a  typical,  portion  of  the  marine  deposits 
which  must  have  been  accumulated  in  some  area  at  present 
unknown  to  us  during  the  period  which  elapsed  between  the 
formation  of  the  great  marine  limestones  of  the  Lower  Carbon- 
iferous and  the  open-sea  and  likewise  calcareous  sediments  of 
the  Middle  Trias. 

The  Permian  rocks  exhibit  their  most  typical  features  in 
Russia  and  Germany,  though  they  are  very  well  developed  in 
parts  of  Britain,  and  they  occur  in  North  America.  When 
well  developed,  they  exhibit  three  main  divisions :  a  lower  set 
of  sandstones,  a  middle  group,  generally  calcareous,  and  an 
upper  series  of  sandstones,  constituting  respectively  the  Lower, 
Middle,  and  Upper  Permians. 

In  Russia,  Germany,  and  Britain,  the  Permian  rocks  con- 
sist of  the  following  members : — 

1.  The  Lower  Permians,  consisting  mainly  of  a  great  series 
of   sandstones,  of   different  colors,  but  usually  red.     The  base 
of    this    series    is    often    constituted    by    massive    breccias    with 
included   fragments   of   the   older   rocks,   upon    which   they   may 
happen    to    repose;    and    similar    breccias    sometimes    occur    in 
the  upper  portion  of  the  series  as  well.     The  thickness  of  this 
group   varies   a   good   deal,    but   may   amount   to   3000   or   4000 
feet. 

2.  The    Middle    Permians,    consisting,    in    their    typical    de- 
velopment,   of    laminated    marls,    or    "  marl-slate, "    surmounted 
by  beds  of  magnesian  limestone   (the  "  Zechstein  "  of  the  Ger- 
man geologists).     Sometimes  the   limestones   are   degenerate  or 
wholly    deficient,    and    the    series    may    consist    of    sandy    shales 
and  g)^psiferous  clays.     The   magnesian   limestone,   however,   of 
the   Middle   Permians  is,   as  a  rule,   so  well  marked  a   feature 
that  it  was  long  spoken  of  as  the  Magnesian  Limestone. 

3.  The  Upper  Permians,  consisting  of  a  series  of  sandstones 


THE  PERMIAN  PERIOD. 


199 


and  shales,  or  of  red  or  mottled  marls,  often  gypsiferous,  and 
sometimes  including  becjs  of  limestone. 

In  North  America,  the  Permian  rocks  appear  to  be  confined 
to  the  region  west  of  the  Mississippi,  being  especially  well  de- 
veloped in  Kansas.  Their  exact  limits  have  not  as  yet  been 
made  out,  and  their  total  thickness  is  not  more  than  a  few 
hundred  feet.  They  consist  of  sandstones,  conglomerates, 
limestones,  marls,  and  beds  of  gypsum.  , 

The  following  diagrammatic  section  shows  the  general 
sequence  of  the  Permian  deposits  in  the  north  of  England, 
where  the  series  is  extensively  developed  (fig.  133)  : — 

GENERALIZED  SECTION  OF  THE  PERMIAN  ROCKS  IN 
THE  NORTH  OF  ENGLAND. 

Fig.  133. 


,»,..  I  Upper      Red      Sand- 
1     stones    and    Marls. 


••  Magnesian    Limestone. 


Marl  Slate. 


( Lower     Red     Sand- 
{     stones  and  Breccias. 


— -  Coal-measures. 


200 


HISTORICAL  PALEONTOLOGY. 


The  record  of  the  life  of  the  Permian  period  is  but  a  scanty 
one,  owing  doubtless  to  the  special  peculiarities  of  such  of  the 
deposits  of  this  age  with  which  we  are  as  yet  acquainted.  Red 
rocks  are,  as  a  general  rule,  more  or  less  completely  unfossil- 
iferous,  and  sediments  of  this  nature  are  highly  characteristic  of 
the  Permian.  Similarly,  magnesian  limestones  are  rarely  as 
highly  charged  with  organic  remains  as  is  the  case  with  normal 
calcareous  deposits,  especially  when  they  have  been  subjected 
to  concretionary  action,  as  is  observable  to  such  a  marked  ex- 
tent in  the  Permian  limestones.  Nevertheless,  much  interest 
is  attached  to  the  organic  remains,  as  marking  a  kind  of  transi- 
tion-period between  the  Palaeozoic  and  Mesozoic  epochs. 

The  plants  of  the  Permian  period,  as  a  whole,  have  a  dis- 
tinctly Palaeozoic  aspect,  and  are  far  more  nearly  allied  to  those 
of  the  Coal-measures  than  they  are  to  those  of  the  earlier 
Secondary  rocks ;  though  the  Permian  species  are  mostly  dis- 
tinct from  the  Carboniferous,  and  there  are  some  new  genera. 
Thus,  we  find  species  of  Lepidodendron,  Catamites,  Equisetites, 
Asterophyllites,  Annularia,  and  other  highly  characteristic 
Carboniferous  genera.  On  the  other  hand,  the  Sigillarioids  of 
the  Coal  seem  to  have  finally  disappeared  at  the  close  of  the 


Fig.  134.— Walchia  pinijormis,  from  the  Permian  of  Saxony, 
a,  Branch  ;  b,  Twig.    (After  Gutbier.) 


Carboniferous  period.  Ferns  are  abundant  in  the  Permian 
rocks,  and  belong  for  the  most  part  to  the  well-known  Carbon- 
iferous genera  Alethopteris,  Neuropteris,  Sphenopteris,  and  Pecop- 
teris.  There  are  also  Tree-ferns  referable  to  ancient  genus 
Psaronius.  The  Conifers  of  the  Permian  period  are  numerous, 


THE  PERMIAN  PERIOD.  201 

and  belong  in  part  to  Carboniferous  genera.  A  characteristic 
genus,  however,  is  Walchia  (fig.  134),  distinguished  by  its  lax 
short  leaves.  This  genus,  though  not  exclusively  Permian,  is 
mainly  so,  the  best-known  species  being  the  W.  piniformis. 
Here,  also,  we  meet  with  Conifers  which  produce  true  cones, 
and  which  differ,  therefore,  in  an  important  degree  from  the 
Taxoid  Conifers  of  the  Coal-measures.  Besides  Walchia,  a 
characteristic  form  of  these  is  the  Ullmania  selaginoides,  which 
occurs  in  the  Magnesian  Limestone  of  Durham,  the  Middle 
Permian  of  Westmorland,  and  the  "  Kupfer-schiefer "  of  Ger- 
many. The  group  of  the  Cycads,  which  we  shall  subsequently 
find  to  be  so  characteristic  of  the  vegetation  of  the  Secondary 
period,  is,  on  the  other  hand,  only  doubtfully  represented  in 
the  Permian  deposits  by  the  singular  genus  Nceggerathia. 

The  Protozoans  of  the  Permian  rocks  are  few  in  number,  and 
for  the  most  part  imperfectly  known.  A  few  Foraminifera  have 
been  obtained  from  the  Magnesian  Limestone  of  England, 
and  the  same  formation  has  yielded  some  ill-understood 
Sponges.  It  does  not  seem,  however,  altogether  impossible 
that  some  of  the  singular  "  concretions  "  of  this  formation  may 
ultimately  prove  to  have  an  organic  structure,  though  others 
would  appear  to  be  clearly  of  purely  inorganic  origin.  From 
the  Permian  of  Saxony,  Professor  Geinitz  has  described  two 
species  of  Spongillopsis,  which  he  believes  to  be  most  nearly 
allied  to  the  existing  fresh-water  Sponges  (Spongilla).  This 
observation  has  an  interest  as  bearing  upon  the  mode  of  de- 
position and  origin  of  the  Permian  sediments. 

The  Ccelenterates  are  represented  in  the  Permian  by  but  a 
few  Corals.  These  belong  partly  to  the  Tabulate  and  partly 
to  the  Rugose  division ;  but  the  latter  great  group,  so  abun- 
dantly represented  in  Silurian,  Devonian,  and  Carboniferous 
seas,  is  now  extraordinarily  reduced  in  numbers,  the  British 
strata  of  this  age  yielding  only  species  of  the  single  genus 
Polyccclia.  So  far,  therefore,  as  at  present  known,  all  the 
characteristic  genera  of  the  Rugose  Corals  of  the  Carboniferous 
had  become  extinct  before  the  deposition  of  the  limestones  of 
the  Middle  Permian. 

The  Echinodcrms  are  represented  by  a  few  Crinoids,  and  by  a 
Sea-urchin  belonging  to  the  genus  Eocidaris.  The  latter  genus 
is  nearly  allied  to  the  Archceocidaris  of  the  Carboniferous,  so 
that  this  Permian  form  belongs  to  a  characteristically  Palaeozoic 
type. 

A  few  Annelides   (Spirorbis,  Vermilia,  &c.)   have  been  de- 


202 


HISTORICAL  PALEONTOLOGY. 


scribed,  but  are  of  no  special  importance.  Amongst  the 
Crustaceans,  however,  we  have  to  note  the  total  absence  of 
the  great  Palaeozoic  group  of  the  Trilobites;  whilst  the  little 
Ostracoda  and  Phyllopods  still  continue  to  be  represented. 
We  have  also  to  note  the  first  appearance  here  of  the  "  Short- 
tailed"  Decapods  or  Crabs  (Brachyura),  the  highest  of  all  the 
groups  of  Crustacea,  in  the  person  of  Hemitrochiscus  paradoxus, 
an  extremely  minute  Crab  from  the  Permian  of  Germany. 

Amongst  the  Mollusca,  the  remains  of  Polyzoa  may  fairly  be 
said  to  be  amongst  the  most  abundant  of  all  the  fossils  of  the 
Permian  formation.  The  principal  forms  of  these  are  the 
fronds  of  the  Lace-corals  (Fenestella,  Retepora,  and  Synocladia), 
which  are  very  abundant  in  the  Magnesian  Limestone  of  the 
north  of  England,  and  belong  to  various  highly  characteristic 
species  (such  as  Fenestella  retiformis,  Retepora  Ehrenbergi,  and 
Synocladia  virgulacea).  The  Brachiopoda  are  also  represented 
in  moderate  numbers  in  the  Permian.  Along  with  species  of 
the  persistent  genera  Discina  Crania,  and  Lingula,  we  still 
meet  with  representatives  of  the  old  groups  Spirifera,  Athyris, 
and  Streptorhynchus ;  and  the  Carboniferous  Products  yet 
survive  under  well-marked  and  characteristic  types,  though  in 
much-diminished  numbers.  The  species  of  Brachiopods  here 
figured  (fig.  135)  are  characteristic  of  the  Magnesian  Limestone 
in  Britain  and  of  the  corresponding  strata  on  the  Continent. 


Fig.  135. — Brachiopods  of  the  Permian  formation,  a,  Producta  horrida;  b,  Lingula 
Credneri;  c,  Perebratula  elongata;  dand  e,  Camarophoria  globulina.     (After  King.) 

Upon  the  whole,  the  most  characteristic  Permian  Brachiopods 
belong  to  the  genera  Producta,  Strophalosia,  and  Camaro- 
phoria. 

The  Bivalves    (Lamellibranchiata}    have   a  tolerably  varied 


THE  PERMIAN  PERIOD. 


203 


development  in  the  Permian  rocks;  but  nearly  all  the  old 
types,  except  some  of  those  which  occur  in  the  Carboniferous, 
have  now  disappeared.  The  principal  Permian  Bivalves 
belong  to  the  groups  of  the  Pearl  Oysters  (Aviculida)  and  the 
Trigoniadtf,  represented  by  genera  such  as  Bakewellia  and 
Schizodus;  the  true  Mussels  (Mytilida),  represented  by  species 
which  have  been  referred  to  Mytilus  itself;  and  the  Arks 
(Arcadce),  represented  by  species  of  the  genera  Area  (fig.  136) 
and  Byssoarca.  The  first  and  last  of  these  three  families  have 
a  very  ancient  origin ;  but  the  family  of  the  Trigoniadce,  though 
feebly  represented  at  the  present  day,  is  one  which  attains  its 
maximum  development  in  the  Mesozoic  period. 

The  Univalves  (Gasteropoda)  are  rare,  and  do  not  demand 
special  notice.  It  may  be  ob- 
served, however,  that  the  Palaeo- 
zoic genera  Euomphalus,  Mur- 
chisonia,  Loxonema,  and 
Macrocheilus  are  still  in  exist- 
ence, together  with  the  per- 
sistent genus  Pleurotomaria. 
Pteropods  of  the  old  genera 
Theca  and  Conularia  have  been 
discovered;  but  the  first  of 
these  characteristically  Palaeo- 
zoic types  finally  dies  out  here,  Fig.  136.— Area  antigua.  Permian, 
and  the  second  only  survives 
but  a  short  time  longer.  Lastly,  a  few  Cephalopods  have  been 


Fig.  137. — Platysomus  gibbosua,  a  "  heterocercal  "  Ganoid,  from  the 
Middle  Permian  of  Russia. 


found,  still  wholly  referable  to  the  Tetrabranchiate  group,  and 


204  HISTORICAL  PALAEONTOLOGY. 

belonging  to  the  old  genera  Orthoceras  and  Cyrtoceras  and  the 
long-lived  Nautilus. 

Amongst  Vertebrates,  we  meet  in  the  Permian  period  not 
only  with  the  remains  of  Fishes  and  Amphibians,  but  also,  for 
the  first  time,  with  true  Reptiles.  The  Fishes  are  mainly 
Ganoids,  though  there  are  also  remains  of  a  few  Cestraciont 
Sharks.  Not  only  are  the  Ganoids  still  the  predominant  group 
of  Fishes,  but  all  the  known  forms  possess  the  unsymmetrical 
("  heterocercal ")  tail  which  is  so  characteristic  of  the  Palaeozoic 
Ganoids.  Most  of  the  remains  of  the  Permian  Fishes  have 
been  obtained  from  the  "  Marl-slate "  of  Durham  and  the 
corresponding  "  Kupfer-schief er "  of  Germany,  on  the  horizon 
of  the  Middle  Permian ;  and  the  principal  genera  of  the  Ganoids 
are  Palaoniscus  and  Platysomus  (fig.  137). 

The  Amphibians  of  the  Permian  period  belong  principally 
to  the  order  of  the  Labyrinthodonls,  which  commenced  to  be 
represented  in  the  Carboniferous,  and  has  a  large  development 
in  the  Trias.  Under  the  name,  however,  of  Paloeosiren  Beinerti, 
Professor  Geinitz  has  described  an  Amphibian  from  the  Lower 
Permian  of  Germany,  which  he  believes  to  be  most  nearly 
allied  to  the  existing  "  Mud-eel "  (Siren  lacertina}  of  North 
America,  and  therefore  to  be  related  to  the  Newts  and  Sala- 
manders (Urodela). 

Finally,  we  meet  in  the  Permian  deposits  with  the  first  un- 
doubted remains  of  true  Reptiles.  These  are  distinguished,  as 
a  class,  from  the  Amphibians,  by  the  fact  that  they  are  air- 
breathers  throughout  the  whole  of  their  life,  and  therefore  are 
at  no  time  provided  with  gills ;  whilst  they  are  exempt  from 
that  metamorphosis  which  all  the  Amphibia  undergo  in  early 
life,  consequent  upon  their  transition  from  an  aquatic  to  a 
more  or  less  purely  aerial  mode  of  respiration.  Their  skel- 
eton is  well  ossified ;  they  usually  have  horny  or  bony  plates, 
singly  or  in  combination,  developed  in  the  skin;  and  their 
limbs  (when  present)  are  never  either  in  the  form  of  fins  or 
wings,  though  sometimes  capable  of  acting  in  either  of  these 
capacities,  and  liable  to  great  modifications  of  form  and  struc- 
ture. Though  there  can  be  no  doubt  whatever  as  to  the  occur- 
rence of  genuine  Reptiles  in  deposits  of  unquestionable  Per- 
mian age,  there  is  still  uncertainty  as  to  the  precise  number 
of  types  which  may  have  existed  at  this  period.  This  uncer- 
tainty arises  partly  from  the  difficulty  of  deciding  in  all  cases 
whether  a  given  bone  be  truly  Labyrinthodont  or  Reptilian, 
but  more  especially  from  the  confusion  which  exists  at  pres- 


THE  PERMIAN  PERIOD. 


205 


ent  between  the  Permian  and  the  overlying  Triassic  deposits. 
Thus  there  are  various  deposits  in  different  regions  which 
have  yielded  the  remains  of  Reptiles,  and  which  cannot  in 
the  meanwhile  be  definitely  referred  either  to  the  Permian 
series  or  to  the  Trias  by  clear  stratigraphical  or  palseonto- 


Fig.  l38.—Protoro8auru8  Speneri,  Middle  Permian,  Thuringla,  reduced  in  size. 
(After  Von  Meyer.)     [Copied  from  Dana.] 


logical  evidence.  All  that  can  be  done  in  such  cases  is  to  be 
guided  by  the  characters  of  the  Reptiles  themselves,  and  to 
judge  by  their  affinities  to  remains  from  known  Triassic  or  Per- 


206  HISTORICAL  PALEONTOLOGY. 

mian  rocks  to  which  of  these  formations  the  beds  containing 
them  should  be  referred;  but  it  is  obvious  that  this  method 
of  procedure  is  seriously  liable  to  lead  to  error.  In  accor- 
dance, however,  with  this,  the  only  available  mode  of  deter- 
mination in  some  cases,  the  remains  of  Thecodontosaurus  and 
Palaosaurus  discovered  in  the  dolomitic  conglomerates  near 
Bristol  will  be  considered  as  Triassic,  thus  leaving  Protoro- 
saurus  *  as  the  principal  and  most  important  representative  of 
the  Permian  Reptiles,  f  The  type-species  of  the  genus  Pro- 
torosaurns  is  the  P.  Speneri  (fig.  138)  of  the  "'  Kupfer-schiefer  "  of 
Thuringia,  but  other  allied  species  have  been  detected  in  the 
Middle  Permian  of  Germany  and  the  north  of  England.  This 
Reptile  attained  a  length  of  from  three  to  four  feet ;  and  it  has 
been  generally  referred  to  the  group  of  the  Lizards  ( Lac ert ilia}, 
to  which  it  is  most  nearly  allied  in  its  general  structure,  at  the 
same  time  that  it  differs  from  all  existing  members  of  this  group 
in  the  fact  that  its  numerous  conical  and  pointed  teeth  were 
implanted  in  distinct  sockets  in  the  jaws — this  being  a  Croco- 
dilian character.  In  other  respects,  however,  Protorosaurus 
approximates  closely  to  the  living  Monitors  (Varanida}  ;  and 
the  fact  that  the  bodies  of  the  vertebrae  are  slightly  cupped  or 
hollowed  out  at  the  ends  would  lead  to  the  belief  that  the 
animal  was  aquatic  in  its  habits.  At  the  same  time,  the 
structure  of  the  hind-limbs  and  their  bony  supports  proves 
clearly  that  it  must  have  also  possessed  the  power  of  progres- 
sion upon  the  land.  Various  other  Reptilian  bones  have  been 
described  from  the  Permian  formation,  of  which  some  are  prob- 
ably really  referable  to  Labyrinthodonts,  whilst  others  are 
regarded  by  Professor  Owen  as  referable  to  the  order  of  the 
"  Theriodonts, "  in  which  the  teeth  are  implanted  in  sockets, 
and  resemble  those  of  carnivorous  quadrupeds  in  consisting 
of  three  groups  in  each  jaw  (namely,  incisors,  canines,  and 
molars).  Lastly,  in  red  sandstones  of  Permian  age  in  Dum- 
friesshire have  been  discovered  the  tracks  of  what  would  ap- 


*  Though  commonly  spelt  as  above,  it  is  probable  that  the  name  of 
this  Lizard  was  really  intended  to  have  been  Proterosaurus — from  the  Greek 
prof  eras,  first ;  and  saura,  lizard :  and  this  spelling  is  followed  by  many 
writers. 

t  In  ah  extremely  able  paper  upon  the  subject  (Quart.  Journ.  Geol. 
Soc.,  vol.  xxvi.),  Mr.  Etheridge  has  shown  that  there  are  good  physical 
grounds  for  regarding  the  dolomitic  conglomerate  of  Bristol  as  of  Triassic 
age,  and  as  probably  corresponding  in  time  with  the  Muschelkalk  of  the 
Continent. 


THE  PERMIAN  PERIOD.  207 

pear  to  have  been  Chelonians  (Tortoises  and  Turtles)  ;  but  it 
would  not  be  safe  to  accept  this  conclusion  as  certain  upon  the 
evidence  of  footprints  alone.  The  Chelichnus  Duncani,  how- 
ever, described  by  Sir  William  Jardine  in  his  magnificent  work 
on  the  '  Ichnology  of  Annandale, '  bears  a  great  resemblance 
to  the  track  of  a  Turtle. 

No    remains   of    Birds    or    Quadrupeds   have   hitherto   been 
detected  in  deposits  of  Permian  age. 


LITERATURE. 


The  following  works  may  be  consulted  by  the  student  with 
regard  to  the  Permian  formation  and  its  fossils: — 

1 i )  "On  the  Geological  Relations  and  Internal  Structure  of 

the  Magnesian  Limestone  and  the  Lower  Portions  of 
the  New  Red  Sandstone  Series,  &c. " — '  Trans.  Geol. 
Soc., '  ser.  2,  vol.  iii.  Sedgwick. 

(2)  '  The    Geology    of    Russia    in    Europe. '      Murchison,    De 

Verneuil,  and  von  Keyserling. 

(3)  '  Siluria. '     Murchison. 

(4)  '  Das  Permische  System  in  Sachsen. '  Geinitz  and  Gutbier. 

(5)  'Die   Versteinerungen   des   Deutschen   Zechsteingebirges. ' 

Geinitz. 

(6)  '  Die  Animalischen  Ueberreste  der  Dyas. '    Geinitz. 

(7)  '  Monograph  of  the  Permian  Fossils  of  England'  Palaeon- 

tographical  Society).    King. 

(8)  '  Monograph    of    the    Permian    Brachiopoda    of    Britain ' 

(Palaeontographical  Society).     Davidson. 

(9)  "On  the  Permian  Rocks  of  the  North-West  of  England 

and  their  Extension  into  Scotland " — '  Quart.  Journ. 
Geol.  Soc., '  vol.  xx.  Murchison  and  Harkness. 

(10)  'Catalogue  of  the  Fossils  of  the  Permian  System  of  the 

Counties  of  Northumberland  and  Durham. '  Howse. 

(11)  '  Petrefacta  Germanise. '    Goldfuss. 

(12)  '  Beitrage  zur  Petref aktenkunde. '     Miinster. 

(13)  '  Ein    Beitrag    zur    Palaeontologie    des    Deutschen    Zech- 

steingebirges. '  Von  Schauroth. 

(14)  '  Saurier  aus  dem  Kupfer-schiefer  der  Zechstein-forma- 

tion. '    Von  Meyer. 

(15)  'Manual  of  Palaeontology.'     Owen. 

(16)  'Recherches  sur  les  Poissons  Fossiles. '    Agassiz. 


208  HISTORICAL  PALAEONTOLOGY. 

(17)  '  Ichnology  of  Annandale. '    Sir  William  Jardine. 

(18)  'Die  Fossile  Flora  der  Permischen  Formation.'  Goeppert 

(19)  'Genera  et  Species  I^lantarum  Fossilium. '  Unger. 

(20)  "  On  the  Red  Rocks  of  England  of  older  Date  than  the 

Trias  " — '  Quart.  Journ.  Geol.  Soc., '  vol.  xxvii.    Ramsay. 


CHAPTER  XV. 


THE  TRIASSIC  PERIOD. 


We  come  now  to  the  consideration  of  the  great  Mesozoic,  or 
Secondary  series  of  formations,  consisting,  in  ascending  order, 
of  the  Triassic,  Jurassic,  and  Cretaceous  systems.  The  Trias- 
sic  group  forms  the  base  of  the  Mesozoic  series,  and  corre- 
sponds with  the  higher  portion  of  the  New  Red  Sandstone  of 
the  older  geologists.  Like  the  Permian  rocks,  and  as  implied 
by  its  name,  the  Trias  admits  of  a  subdivision  into  three 
groups — a  Lower,  Middle,  and  Upper  Trias.  Of  these  sub- 
divisions the  middle  one  is  wanting  in  Britain;  and  all  have 
received  German  names,  being  more  largely  and  typically  de- 
veloped in  Germany  than  in  any  other  country.  Thus,  the 
Lower  Trias  is  known  as  the  Bunter  Sandstein;  the  Middle 
Trias  is  called  the  Muschelkalk;  and  the  Upper  Trias  is  known 
as  the  Keuper. 

I.  The  lowest  division  of  the  Trias  is  known  as  the  Bunter 
Sandstein  (the  Gres  bigarre  of  the  French),  from  the  generally 
variegated  colors  of  the  beds  which  compose  it  (German, 
bunt,  variegated).  The  Bunter  Sandstein  of  the  continent  of 
Europe  consists  of  red  and  white  sandstones,  with  red  clays, 
and  thin  limestones,  the  whole  attaining  a  thickness  of  about 
1500  feet.  The  term  "  marl "  is  very  generally  employed  to 
designate  the  clays  of  the  Lower  and  Upper  Trias ;  but  the 


THE  TRIASSIC  PERIOD.  209 

term  is  inappropriate,  as  they  may  contain  no  lime,  and  are 
therefore  not  always  genuine  marls.  In  Britain  the  Bunter 
Sandstein  consists  of  red  and  mottled  sandstones,  with  uncon- 
solidated  conglomerates,  or  "  pebble-beds, "  the  whole  having 
a  thickness  of  1000  to  2000  feet.  The  Bunter  Sandstein,  as 
a  rule,  is  very  barren  of  fossils. 

II.  The    Middle   Trias   is   not   developed   in   Britain,   but   it 
is  largely  developed  in  Germany,  where  it  constitutes  what  is 
known  as  the  Muschelkalk  (Germ.  Muschel,  mussel;    kalk,  lime- 
stone), from  the  abundance  of  fossil  shells  which  it  contains. 
The  Muschelkalk  (the  Calcaire  coquillier  of  the  French)  consists 
of  compact  grey  or  yellowish  limestones,  sometimes  dolomitic, 
and  including  occasional  beds  of  gypsum  and  rock-salt. 

III.  The  Upper  Trias,  or  Keuper  (the  Marnes  irisees  of  the 
French),   as   it   is  generally  called,   occurs   in   England;   but  is 
not   so   well    developed   as   it   is   in   Germany.     In    Britain,   the 
Keuper  is  1000  feet  or  more  in  thickness,  and  consists  of  white 
and   brown    sandstones    with    red    marls,    the   whole    topped   by 
red  clays  with  rock-salt  and  gypsum. 

The  Keuper  in  Britain  is  extremely  unfossiliferous ;  but  it 
passes  upwards  with  perfect  conformity  into  a  very  remarkable 
group  of  beds,  at  one  time  classed  with  the  Lias,  and  now 
known  under  the  names  of  the  Penarth  beds  (from  Penarth,  in 
Glamorganshire),  the  Rhaetic  beds  (from  the  Rhaetic  Alps),  or 
the  Avicula  contorta  beds  (from  the  occurrence  in  them  of 
great  numbers  of  this  peculiar  Bivalve).  These  singular  beds 
have  been  variously  regarded  as  the  highest  beds  of  the  Trias, 
or  the  lowest  beds  of  the  Lias,  or  as  an  intermediate  group. 
The  phenomena  observed  on  the  Continent,  however,  render 
it  best  to  consider  them  as  Triassic,  as  they  certainly  agree 
with  the  so-called  Upper  St.  Cassian  or  Kossen  beds  which 
form  the  top  of  the  Trias  in  the  Austrian  Alps. 

The  Penarth  beds  occur  in  Glamorganshire,  Gloucestershire, 
Warwickshire,  Staffordshire,  and  the  north  of  Ireland;  and 
they  generally  consist  of  a  small  thickness  of  grey  marls,  white 
limestones,  and  black  shales,  surmounted  conformably  by  the 
lowest  beds  of  the  Lias.  The  most  characteristic  fossils  which 
they  contain  are  the  three  Bivalves  Cardium  Rhceticum,  Avicula 
contorta,  and  Pecten  Valoniensis;  but  they  have  yielded  many 
other  fossils,  amongst  which  the  most  important  are  the  re- 
mains of  Fishes  and  small  Mammals  (Microlestes). 

In  the  Austrian  Alps  the  Trias  terminates  upwards  in  an 
extraordinary  series  of  fossiliferous  beds,  replete  with  marine 
14 


210 


HISTORICAL    PALEONTOLOGY. 


fossils.     Sir   Charles   Lyell   gives   the   following   table   of  these 
remarkable  deposits : — 


Strata  below  the  Lias 


Kossen  beds, 

(Synonyms,  Up- 
per St  Cassian 
beds  of  Escher 
and  Merian.) 


2.  Dachstein  beds. 


3.  Hallstadt  beds 
(or  St  Cassian), 


4.  A.    Guttenstein 

beds. 
B.  Werfen  beds, 

base  of  Upper 

Trias  ? 
Lower  Trias  of 

some  geologists. 


in  the  Austrian  Alps,  in  descending  order. 

(  Grey  and  black  limestone,  with  calcar- 
eous marls  having  a  thickness  of 
about  50  feet.  Among  the  fossils, 
Brachiopoda  very  numerous ;  some 
few  species  common  to  the  genuine 
Lias;  many  peculiar.  Avicula  con- 
torta,  Pecten  Valoniensis,  Cardium 
Rh&ticum,  Avicula  inaquivalvis,  Spir- 
ifer  Munsteri,  Dev.  Strata  contain- 
ing the  above  fossils  alternate  with 
the  Dachstein  beds,  lying  next  below. 

White  or  greyish  limestone,  often  in 
beds  three  or  four  feet  thick.  Total 
thickness  of  the  formation  above 
2000  feet.  Upper  part  fossiliferous, 
with  some  strata  composed  of  corals 
(Lithodendron.)  Lower  portion  with- 
out fossils.  Among  the  character- 
istic shells  are  Hemicardium  Wulfeni, 
Megalodon  triqueter,  and  other  large 
bivalves. 

Red,  pink,  or  white  marbles,  from  800 
to  1000  feet  in  thickness,  containing 
more  than  800  species  of  marine  fos- 
sils, for  the  most  part  mollusca.  Many 
species  of  Orthoceras.  True  Am- 
monites, besides  Ceratites  and  Gon- 
iatites,  Belemnites  (rare),  Porcellia, 
Pleurotomaria,  Trochus,Monotis  Sali- 
11  ana,  &c 

A.  Black      and      grey 
limestone     150     feet 
thick,  alternating  with 
the   underlying  Wer- 
fen beds. 

B.  Red     and     green 
shale   and   sandstone, 
with    salt    and    gyp- 
sum. 


Among  the  fossils 
are  Ceratite* 
cassianua.  My- 
acites  fassaen- 
8i8,  Naticella 
costata,  dec. 


J 


In  the  United  States,  rocks  of  Triassic  age  occur  in  several 
areas  between  the  Appalachians  and  the  Atlantic  seaboard; 
but  they  show  no  such  triple  division  as  in  Germany,  and  their 
exact  place  in  the  system  is  uncertain.  The  rocks  of  these 
areas  consist  of  red  sandstones,  sometimes  shaly  or  conglomer- 
atic, occasionally  with  beds  of  impure  limestone.  Other  more 
extensive  areas  where  Triassic  rocks  appear  at  the  surface,  are 
found  west  of  the  Mississippi,  on  the  slopes  of  the  Rocky  Moun- 


THE  TRIASSIC  PERIOD. 


211 


tains,  where  the  beds  consist  of  sandstones  and  gypsiferous 
marls.  The  American  Trias  is  chiefly  remarkable  for  having 
yielded  the  remains  of  small  Marsupial  (Dromatherium} ,  and 
numerous  footprints,  which  have  generally  been  referred  to 
Birds  (Brontozoum),  along  with  the  tracks  of  undoubted  Rep- 
tiles (Otosoum,  Anisopus,  &c.) 

The  subjoined  section  (fig.  139)  expresses,  in  a  diagram- 
matic manner,  the  general  sequence  of  the  Triassic  rocks  when 
fully  developed,  as,  for  example,  in  the  Bavarian  Alps: — 

GENERALIZED  SECTION  OF  THE  TRIASSIC  ROCKS  OF 

CENTRAL  EUROPE. 

Fig.  139- 


Upper  Keuper  (Kos- 
sen  or  Rhsetic  beds, 
and  Dachsteln  beds). 


'-  \    n 


i — i — T— T 


JLJLJLji 


rnr-r 


\\'     \ 


1... 


Middle  Keuper  (Hall- 
stadt  or  St.  Cassian 
beds). 


j  Lower  Keuper  (Keuper 
I      Sandstones    proper). 


Muschelkalk. 


/  Bunter  Sandstein.  Gut- 
tenstein  and  Werfen 
beds?) 


With  regard  to  the  life  of  the  Triassic  period,  we  have  to 


212  HISTORICAL  PALEONTOLOGY. 

notice  a  difference  as  concerns  the  different  members  of  the 
group  similar  to  that  which  has  been  already  mentioned  in 
connection  with  the  Permian  formation.  The  arenaceous 
deposits  of  the  series,  namely,  resemble  those  of  the  Permian, 
not  only  in  being  commonly  red  or  variegated  in  their  color, 
but  also  in  their  conspicuous  paucity  of  organic  remains. 
They  for  the  most  part  are  either  wholly  unfossiliferous,  or 
they  contain  the  remains  of  plants  or  the  bones  of  reptiles, 
such  as  may  easily  have  been  drifted  from  some  neighboring 
shore.  The  few  fossils  which  may  be  considered  as  properly 
belonging  to  these  deposits  are  chiefly  Crustaceans  (Estheria) 
or  Fishes,  which  may  well  have  lived  in  the  waters  of  estuaries 
or  vast  inland  seas.  We  may  therefore  conclude,  with  con- 
siderable probability,  that  the  barren  sandy  and  marly  accumu- 
lations of  the  Bunter  Sandstein  and  Lower  Keuper  were  not 
laid  down  in  an  open  sea,  but  are  probably  brackish-water 
deposits,  formed  in  estuaries  or  land-locked  bodies  of  salt 
water.  This  at  any  rate  would  appear  to  be  the  case  as  regards 
these  members  of  the  series  as  developed  in  Britain  and  in 
their  typical  areas  on  the  continent  of  Europe;  and  the  origin 
of  most  of  the  North  American  Trias  would  appear  to  be 
much  the  same.  Whether  this  view  be  correct  or  not,  it  is 
certain  that  the  beds  in  question  were  laid  down  in  shallow 
water,  and  in  the  immediate  vicinity  of  land,  as  shown  by  the 
numerous  drifted  plants  which  they  contain  and  the  common 
occurrence  in  them  of  the  footprints  of  air-breathing  animals 
(Birds,  Reptiles,  and  Amphibians).  On  the  other  hand,  the 
middle  and  the  highest  members  of  the  Trias  are  largely  calca- 
reous, and  are  replete  with  the  remains  of  undoubted  marine 
animals.  There  cannot,  therefore,  be  the  smallest  doubt  but 
that  the  Muschelkalk  and  the  Rhsetic  or  Kossen  beds  were 
slowly  accumulated  in  an  open  sea,  of  at  least  a  moderate 
depth;  and  they  have  preserved  for  us  a  very  considerable 
selection  from  the  marine  fauna  of  the  Triassic  period. 

The  plants  of  the  Trias  are,  on  the  whole,  as  distinctively 
Mesozoic  in  their  aspect  as  those  of  the  Permian  are  Palaeo- 
zoic. Tn  spite,  therefore,  of  the  great  difficulty  which  is  ex- 
perienced in  e-ffecting  a  satisfactory  stratigraphical  separation 
between  the  Permian  and  the  Trias,  we  have  in  this  fact  a 
proof  that  the  two  formations  were  divided  by  an  interval  of 
time  sufficient  to  allow  of  enormous  changes  in  the  terrestrial 
vegetation  of  the  world.  The  Lepidodendroids,  Asterophyllites, 
and  Annularies,  of  the  Goal  and  Permian  formations,  have  now 


THE  TRIASSIC  PERIOD.  213 

apparently  wholly  disappeared ;  and  the  Triassic  flora  consists 
mainly  of  Ferns,  Cycads,  and  Conifers,  of  which  only  the  two 
last  need  special  notice.  The  Cycads  (fig.  140)  are  true  exo- 
genus  plants,  which  in  general  form  and  habit  of  growth  pre- 


Fig.  llQ.—Zamia  spirali»,  a  living  Cycad.    Australia. 

sent  considerable  resemblance  to  young  Palms,  but  which  in 
reality  are  most  nearly  related  to  the  Pines  and  Firs  (Conifers). 
The  trunk  is  unbranched,  often  much  shortened,  and  bears  a 
crown  of  feathery  pinnate  fronds.  The  leaves  are  usually 
"  circinate " — they  unroll  in  expanding,  like  the  fronds  of 
ferns.  The  seeds  are  not  protected  by  a  seed-vessel,  but  are 
borne  upon  the  edge  of  altered  leaves,  or  are  carried  on  the 
scales  of  a  cone.  All  the  living  species  of  Cycads  are  natives 
of  warm  countries,  such  as  South  America,  the  West  Indies, 
Japan,  Australia,  Southern  Asia,  and  South  Africa.  The 
remains  of  Cycads,  as  we  have  seen,  are  not  known  to  occur 
in  the  Coal  formation,  or  only  to  a  very  limited  extent  towards 
its  close;  nor  are  they  known  with  certainty  as  occurring  in 
Permian  deposits.  In  the  Triassic  period,  however,  the  re- 
mains of  Cycads  belonging  to  such  genera  as  Pterophyllum 
(fig.  141,  b),  Zamites,  and  Podozamites  (fig.  141  c),  are  suffi- 
ciently abundant  to  constitute  quite  a  marked  feature  in  the 
vegetation ;  and  they  continue  to  be  abundantly  represented 
throughout  the  whole  Mesozoic  series.  The  name  "  Age  of 
Cycads, "  as  applied  to  the  Secondary  epoch,  is  therefore, 
from  a  botanical  point  of  view,  an  extremely  appropriate  one. 
The  Conifers  of  the  Trias  are  riot  uncommon,  the  principal 
form  being  Voltzia  (fig.  141,  a),  which  possesses  some  peculiar 


214  HISTORICAL  PALAEONTOLOGY. 

characters,  but  would  appear  to  be  mostly  nearly  related  to  the 
recent  Cypresses. 

As  regards  the  Invertebrate  animals  of  the  Trias,  our  knowl- 
edge is  still  principally  derived  from  the  calcareous  beds 
which  constitute  the  center  of  the  system  (the  Muschelkalk) 
on  the  continent  of  Europe,  and  from  the  St.  Cassian  and 
Rhsetic  beds  still  higher  in  the  series;  whilst  some  of  the 


Fig.  141. — Trlassic  Conifers  and  Cycads.  a,  Voltzia  (Schizoneura)  heterophylla, 
portion  of  a  branch,  Europe  and  America  ;  6,  Part  of  the  frond  of  Pterophyllum 
Jcegeri,  Europe  ;  c,  Part  of  the  frond  of  Podozamites  lanceolatus,  America. 

Triassic  strata  of  California  and  Nevada  have  likewise  yielded 
numerous  remains  of  marine  Invertebrates.  The  Protozoans 
are  represented  by  Foraminifera  and  Sponges,  and  the  C&len- 
terates  by  a  small  number  of  Corals;  but  these  require  no 
special  notice.  It  may  be  mentioned,  however,  that  the  great 


THE  TRIASSIC  PERIOD. 


215 


Palaeozoic  group  of  the  Rugose  corals  has  no  known  repre- 
sentative here,  its  place  being  taken  by  corals  of  Secondary 
type  (such  as  Montlivaltia,  Synastraa,  &c.) 

The  Echinoderms  are  represented  principally  by  Crinoids, 
the  remains  of  which  are  extremely  abundant  in  some  of  the 
limestones.  The  best-known  species  is  the  famous  "  Lily- 
Encrinite"  (Encrinus  liUiformis,  fig.  142),  which  is  character- 
istic of  the  Muschelkalk.  In  this  beautiful  species,  the  flower- 
like  head  is  supported  upon  a  rounded  stem,  the  joints  of 
which  are  elaborately  articulated  with  one 
another;  and  the  fringed  arms  are  com- 
posed each  of  a  double  series  of  alter- 
nating calcareous  pieces.  The  Palaeozoic 
Urchins,  with  their  supernumerary  rows  of 
plates,  the  Cystideans,  and  the  Pentremites 
have  finally  disappeared;  but  both  Star- 
fishes and  Brittle-stars  continue  to  be  rep- 


Fig.  143. 


Aipidura   loricata,   a  Triassic    Ophlurold. 
Muschelkalk,  Germany. 


Fig.  142.  — Head  and 
upper  part  of  the  column 
of  Encrinus  liUiformis. 
The  lower  figure  shows 
the  articulating  surface 
of  one  of  the  joints  of  the 
column.  Muschelkalk, 
Germany. 


period.    Remains  of 


resented.  One  of  the  latter — namely,  the 
Asf>idura  loricata  of  Goldfuss  (fig.  143) — is 
highly  characteristic  of  the  Muschelkalk. 

The  remains  of  Articulate  Animals  are 
not  very  abundant  in  the  Trias,  if  we  except 
the  bivalved  cases  of  the  little  Water-fleas 
(Ostracoda),  which  are  occasionally  very 
plentiful.  There  are  also  many  species 
of  the  horny,  concentrically-striated  valves 
of  the  Esthericz  (see  fig.  122,  &),  which 
might  easily  be  taken  for  small  Bivalve 
Molluscs.  The  "  Long-tailed "  Decapods, 
of  the  type  of  the  Lobster,  are  not  with- 
out examples,  but  they  become  much  more 
numerous  in  the  succeeding  Juriassic 
insects  have  also  been  discovered. 


216 


HISTORICAL  PALEONTOLOGY. 


Amongst  the  Mollusca  we  have  to  note  the  disappearance, 
amongst  the  lower  groups,  of  many  characteristic  Palaeozoic 
types.  Amongst  the  Polyzoans,  the  characteristic  "  Lace- 
corals,  "  Fenestella,  Retepora,  *  Synocladia,  Polypora,  &c.,  have 


Fig.  144. — Triassic  Lamellibranchs,  a,  Daonella  (Halobia)  Lommelli  ;  b,  Pecten 
Valoniensis;  c,  Myophoria  lineata;  d,  Cardium  Rhaticum  ;  e,  Avicula  contorta; 
f,  Avicula  socialis. 


become  apparently  extinct.  The  same  is  true  of  many  of  the 
ancient  types  of  Brachiopods,  and  conspicuously  so  of  the 
great  family  of  the  Productida,  which  played  such  an  important 
part  in  the  seas  of  the  Carboniferous  and  Permian  periods. 

Bivalves  (Lamellibranchiata)  and  Univalves  (Gasteropoda} 
are  well  represented  in  the  marine  beds  of  the  Trias,  and 
some  of  the  former  are  particularly  characteristic  either  of  the 


*  The  genus  Retepora  is  really  a  recent  one,  represented  by  living 
forms ;  and  the  so-called  Retepora'  of  the  Palaeozoic  rocks  should  properly 
receive  another  name  (Phyllopora),  as  being  of  a  different  nature.  The 
name  Retepora  has  been  here  retained  for  these  old  forms  simply  in  ac- 
cordance with  general  usage. 


THE  TRIASSIC  PERIOD.  217 

formation  as  a  whole  or  of  minor  subdivisions  of  it.  A  few  of 
these  characteristic  species  are  figured  in  the  accompanying 
illustration  (fig.  144).  Bivalve  shells  of  the  genera  Daonella 
(fig.  144,  a)  and  Halobia  (Monotis)  are  very  abundant,  and  are 
found  in  the  Triassic  strata  of  almost  all  regions.  These 
groups  belong  to  the  family  of  the  Pearl-oysters  (Aviculida}, 
and  are  singular  from  the  striking  resemblance  borne  by  some 
of  their  included  forms  to  the  Strophomena  amongst  the  Lamp- 
shells,  though,  of  course,  no  real  relation  exists  between  the 
two.  The  little  Pearl-oyster,  Avicula  socialis  (fig.  144,  /),  is 
found  throughout  the  greater  part  of  the  Triassic  series,  and  is 
especially  abundant  in  the  Muschelkalk.  The  genus  Myo- 
phoria  (fig.  144,  c),  belonging  to  the  Trigoniadce,  and  related 
therefore  to  the  Permian  Schizodus,  is  characteristically  Trias- 
sic, many  species  of  the  genus  being  known  in  deposits  of  this 
age.  Lastly,  the  so-called  "  Rhaetic "  or  "  Kossen "  beds  are 
characterized  by  the  occurrence  in  them  of  the  Scallop,  Pecten 
Valoniensis  (fig.  144,  b)  ;  the  small  Cockle,  Cardium  Rhceticum 
(fig.  144,  d}  ;  and  the  curiously-twisted  Pearl-oyster,  Avicula 
contorta  (fig.  144,  e) — this  last  Bivalve  being  so  abundant  that 
the  strata  in  question  are  often  spoken  of  as  the  "Avicula 
contorta  beds.  " 

Passing  over  the  groups  of  the  Heteropods  and  Pteropods, 
we  have  to  notice  the  Cephalopoda,  which  are  represented  in 
the  Trias  not  only  by  the  chambered  shells  of  Tetrabranchiates, 
but  also,  for  the  first  time,  by  the  internal  skeletons  of  Dibran- 
chiate  forms.  The  Trias,  therefore,  masks  the  first  recognized 
appearance  of  true  Cuttle-fishes.  All  the  known  examples  of 
these  belong  to  the  great  Mesozoic  group  of  the  Belemnitida; 
and  as  this  family  is  much  more  largely  developed  in  the  suc- 
ceeding Jurassic  period,  the  consideration  of  its  characters 
will  be  deferred  till  that  formation  is  treated  of.  Amongst  the 
chambered  Cephalopods  we  find  quite  a  number  of  the  Palae- 
ozoic Orthoceratites,  some  of  them  of  considerable  size,  along 
with  the  ancient  Cyrtoceras  and  Goniatites;  and  these  old  types, 
singularly  enough,  occur  in  the  higher  portion  of  the  Trias 
(St.  Cassian  beds),  but  have,  for  some  unexplained  reason,  not 
yet  been  recognized  in  the  lower  and  equally  fossiliferous 


218 


HISTORICAL  PALAEONTOLOGY. 


Fig.  145. — Ceratites  nodosus,  viewed  from  the  side 
and  from  behind.    Muschelkalk. 


formation  of  the  Muschelkalk.  Along  with  these  we  meet  for 
the  first  time  with  true  Ammonites,  which  fill  such  an  extensive 
place  in  the  Jurassic 
seas,  and  which  will 
be  spoken  of  here- 
after. The  form,  how- 
ever, which  is  most 
characteristic  of  the 
Trias  is  Ceratites  (fig. 
145).  In  this  genus 
the  shell  is  curved  into 
a  flat  spiral,  the  volu- 
tions of  which  are  in 
contact ;  and  it  further 
agrees  with  both  Go- 
niatites  and  Ammon- 
ites in  the  fact  that  the 
septa  or  partitions  be- 
tween the  air-cham- 
bers are  not  simple  and  plain  (as  in  the  Nautilus  and  its  allies), 
but  are  folded  and  bent  as  they  approach  the  outer  wall  of  the 
shell.  In  the  Goniatite  these  foldings  of  the  septa  are  of  a  simply 
lobed  or  angulated  nature,  and  in  the  Ammonite  they  are  ex- 
tremely complex;  whilst  in  the  Ceratite  there  is  an  inter- 
mediate state  of  things,  the  special  feature  of  which  is,  that 
those  foldings  which  are  turned  towards  the  mouth  of  the 
shell  are  merely  rounded,  whereas  those  which  are  turned 
away  from  the  mouth  are  characteristically  toothed.  The 
genus  Ceratites,  though  principally  Triassic,  has  recently  been 
recognized  in  strata  of  Carboniferous  age  in  India. 

From  the  foregoing  it  will  be  gathered  that  one  of  the  most 
important  points  in  connection  with  the  Triassic  Mollusca  is 
the  remarkable  intermixture  of  Palaeozoic  and  Mesozoic  types 
which  they  exhibit.  It  is  to  be  remembered,  also,  that  this 
intermixture  has  hitherto  been  recognized,  not  in  the  Middle 
Triassic  limestones  of  the  Muschelkalk,  in  which — as  the 
oldest  Triassic  beds  with  marine  fossils — we  should  naturally 
expect  to  find  it,  but  in  the  St.  Cassian  beds,  the  age  of  which 
is  considerably  later  than  that  of  the  Muschelkalk.  The 
intermingling  of  old  and  new  types  of  Shell-fish  in  the  Upper 
Trias  is  well  brought  out  in  the  annexed  table,  given  by  Sir 


THE  TRIASSIC  PERIOD. 


219 


Charles    Lyell   in   his   'Student's    Elements   of    Geology'    (some 
of  the  less  important  forms  in  the  table  being  omitted  here)  : — 


GENERA  OF  FOSSIL  MOLLUSCA  IN  THE  ST.  CASSIAN 
AND  HALLSTADT  BEDS. 


Common  to  Older  Bocks. 

Orthoceras. 

Bactrites. 

Macrocheilus. 

Loxonema. 

Holopella. 

Murchisonia. 

Porcellia. 

Athyris. 

Retzia. 

Cyrtina. 

Euomphalus. 


Characteristic  of  Triassic 
Rocks. 

Common  to  Newer  Bocks. 

Ceratites.   . 

Ammonites. 

Cochloceras. 

Chemnitzia. 

Rhabdoceras. 

Cerithium. 

Aulacoceras. 

Monodonta. 

Naticella. 

Sphoera. 

Platystoma. 

Cardita. 

Halobia. 
Hornesia. 

Myoconcha. 
Hinnites. 

Koninckia. 

Monotis. 

Scoliostoma. 

Plicatula. 

Myophoria. 

Pachyrisma. 

(The  last  two  are 

Thecidium. 

principally      but 

not      exclusively 

Triassic.) 

Thus,  to  emphasize  the  more  important  points  alone,  the  Trias 
has  yielded,  amongst  the  Gasteropods,  the  characteristically 
Palaeozoic  Loxoncma,  Holopella,  Murchisonia,  Euomphalus,  and 
Porcellia,  along  with  typically  Triassic  forms  like  Platystoma 
and  Scoliostoma,  and  the  great  modern  groups  Chemnitzia  and 
Cerithium.  Amongst  the  Bivalves  we  find  the  Palaeozoic 
Mcgalodon  side  by  side  with  the  Triassic  Halobia  and  Myo- 
phoria, these  being  associated  with  the  Cardita,  Hinnites, 
Plicatulce,  and  Trigonia  of  later  deposits.  The  Brachiopods 
exhibit  the  Palaeozoic  Athyris,  Retzia,  and  Cyrtina,  with  the 
Triassic  Koninckia  and  the  modern  Thecidium.  Finally,  it  is 
here  that  the  ancient  genera  Orthoceras,  Cyrtoceras,  and  Gonia- 
tites  make  their  last  appearance  upon  the  scene  of  life,  the 
place  of  the  last  of  these  being  taken  by  the  more  complex 
and  almost  exclusively  Triassic  Ceratites;  whilst  the  still  more 
complex  genus  Ammonites  first  appears  here  in  force,  and  is 
never  again  wanting  till  we  reach  the  close  of  the  Mesozoic 
period.  The  first  representatives  of  the  great  Secondary 
family  of  the  Belemnites  are  also  recorded  from  this  horizon. 
Amongst  the  Vertebrate  Animals  of  the  Trias,  the  Fishes  are 


220  HISTORICAL  PALEONTOLOGY. 

represented  by  numerous  forms  belonging  to  the  Ganoids  and 
the  Placoids.  The  Ganoids  of  the  period  are  still  all  provided 
with  unsymmetrical  ("  heterocercal ")  tails,  and  belong  prin- 
cipally to  such  genera  as  Palaoniscus  and  Catopterus.  The 
remains  of  Placoids  are  in  the  form  of  teeth  and  spines,  the 
two  principal  genera  being  the  two  important  Secondary 
groups  Acrodus  and  Hybodus.  Very  nearly  at  the  summit 
of  the  Trias  in  England,  in  the  Rhaetic  series,  is  a  singular 
stratum,  which  is  well  known  as  the  "  bone-bed, "  from  the 
number  of  fish-remains  which  it  contains.  More  interesting, 
however,  than  the  above,  are  the  curious  palate-teeth  of  the 
Trias,  upon  which  Agassiz  founded  the  genus  Ceratodus.  The 
teeth  of  Ceratodus  (fig.  146)  are  singular  flattened  plates, 
composed  of  spongy  bones  beneath,  covered  superficially  with 
a  layer  of  enamel.  Each  plate  is  approximately  triangular, 
one  margin  (which  we  know  to  be  the  outer  one)  being 
prolonged  into  prongs  or  conical  prominences,  whilst  the 
surface  '  is  more  or  less  regularly  undulated.  Until  recently, 
though  the  master-mind  of  Agassiz  recognized  that  these 
singular  bodies  were  undoubtedly  the  teeth  of  fishes,  we  were 
entirely  ignorant  as  to  their  precise  relation  to  the  animal,  or 


Fig.  146. — a,  Dental  plate  of  Ceratodus  serratus,  Keuper  ;  b,  Dental  plate  of 
Ceratodus  altus,  Keuper.     (After  Agassiz.) 


as  to  the  exact  affinities  of  the  fish  thus  armed.  Lately,  how- 
ever, there  has  been  discovered  in  the  rivers  of  Queensland 
(Australia)  a  living  species  of  Ceratodus  (C.  Fosteri,  fig.  147), 
with  teeth  precisely  similar  to  those  of  its  Triassic  predecessor; 
and  we  thus  have  become  acquainted  with  the  use  of  these 
structures  and  the  manner  in  which  they  were  implanted  in 
the  mouth.  The  palate  carries  two  of  these  plates,  with  their 
longer  straight  sides  turned  towards  each  other,  their  sharply- 
sinuated  sides  turned  outwards,  and  their  short  straight  sides 


THE  TRIASSIC  PERIOD.  221 

or  bases  directed  backwards.  Two  similar  plates  in  the  lower 
jaw  correspond  to  the  upper,  their  undulated  surfaces  fitting 
exactly  to  those  of  the  opposite  teeth.  There  are  also  two 
sharp-edged  front  teeth,  which  are  placed  in  the  front  of  the 
mouth  in  the  upper  jaw;  but  these  have  not  been  recognized 
in  the  fossil  specimens.  The  living  Ceratodus  feeds  on  vege- 
table matters,  which  are  taken  up  or  torn  off  from  plants  by 
the  sharp  front  teeth,  and  then  partially  crushed  between  the 
undulated  surfaces  of  the  back  teeth  (Giinther)  ;  and  there 
need  be  little  doubt  but  that  the  Triassic  Ceratodi  followed 
a  similar  mode  of  existence.  From  the  study  of  the  living 
Ceratodus,  it  is  certain  that  the  genus  belongs  to  the  same 
group  as  the  existing  Mud-fishes  (Dipnoi)  ;  and  we  therefore 
learn  that  this,  the  highest,  group  of  the  entire  class  of  Fishes 
existed  in  Triassic  times  under  forms  little  01  not  at  all  differ- 
ent from  species  now  alive ;  whilst  it  has  become  probable 
that  the  order  can  be  traced  back  into  the  Devonian  period. 

The  Amphibians  of  the  Trias  all  belong  to  the  old  order  of 


Fig.  147.— Ceratodus  Foateri,  the  Australian  Mud-fish,  reduced  In  size. 

the  Labyrinthodonts,  and  some  of  them  are  remarkable  for 
their  gigantic  dimensions.  They  were  first  known  by  their 
footprints,  which  were  found  to  occur  plentifully  in  the  Tri- 
assic sandstones  of  Britain  and  the  continent  of  Europe,  and 
which  consisted  of  a  double  series  of  alternately-placed  pairs 
of  hand-shaped  impressions,  the  hinder  print  of  each  pair  being 
much  larger  than  the  one  in  front  (fig.  148).  So  like  were  these 
impressions  to  the  shape  of  the  human  hand,  that  the  at  that 
time  unknown  animal  which  produced  them  was  at  once  chris- 
tened Cheirotherium,  or  "  Hand-beast. "  Further  discoveries, 
however,  soon  showed  that  the  footprints  of  Cheirotherium 
were  really  produced  by  species  of  Amphibians  which,  like  the 
existing  Frogs,  possessed  hind-feet  of  a  much  larger  size  than 


222 


HISTORICAL  PALAEONTOLOGY. 


the  fore-feet  and  to  which  the 
name  of  Labyrinthodonts  was 
applied  in  consequence  of  the 
complex  microscopic  structure  of 
the  teeth  (fig.  149).  In  the  essen- 
tial details  of  their  structure,  the 
Triassic  Labyrinthodonts  did  not 
differ  materially  from  their  pre- 
decessors in  the  Coal-measures 
and  Permian  rocks.  They  pos- 
sessed the  same  frog-like  skulls 
(fig.  150),  with  a  lizard-like  body, 
a  long  tail,  and  comparatively 
feeble  limbs.  The  hind-limbs 
were  stronger  and  longer  than 
the  fore-limbs,  and  the  lower 


Fig.  148.— Footprints  of  a  Labyrinthodont  (Ckeirotherium),  from  the  Triassic  Sand- 
stones of  Hessberg,  near  Hildburghausen.  Germany,  reduced  one-eighth.  The  lower 
figure  shows  a  slab,  with  several  prints,  and  traversed  by  reticulated  sun-cracks  ;  the 
upper  figure  shows  the  impression  of  one  of  the  hind- feet,  one-half  of  the  natural  size. 
(After  Sickler.) 


THE  TRIASSIC  PERIOD. 


223 


surface  of  the  body  was  protected  by  an  armor  of  bony  plates. 
Some  of  the  Triassic  Labyrinthodonts  must  have  attained 
dimensions  utterly  unapproached  amongst  existing  Amphibians, 
the  skull  of  Labyrinthodon  J&geri  (fig.  150)  being  upwards  of 
three  feet  in  length  and  two  feet  in  breadth.  Restorations  of 
some  of  these  extraordinary  creatures  have  been  attempted  in 
the  guise  of  colossal  Frogs;  but  they  must  in  reality  have  more 
closely  resembled  huge  Newts. 

Remains  of  Reptiles  are  very  abundant  in  Triassic  deposits, 
and  belong  to  very  varied  types.  The  most  marked  feature, 
in  fact,  connected  with  the  Vertebrate  fauna  of  the  Trias,  and 
of  the  Secondary  rocks  in  general,  is  the  great  abundance  of 
Reptilian  life.  Hence  the  Secondary  period  is  often  spoken 
of  as  the  "  Agfe  of  Reptiles. "  Many  of  the  Triassic  reptiles 
depart  widely  in  their  structure  from  any  with  which  we  are 
acquainted  as  existing  on  the  earth  at  the  present  day,  and  it  is 
only  possible  here  to  briefly  note  some  of  the  more  important 
of  these  ancient  forms.  Amongst  the  group  of  the  Lizards 
(Lacertilia},  represented  by  Protorosaurus  in  the  older  Permian 
strata,  three  types  more  or  less  certainly  referable  to  this  order 
may  be  mentioned.  One  of  these  is  a  small  reptile  which 


Fig.  149.— Section  of  the  tooth  of  Labyrinthodon 
(Mastodonsaurua)  Jcegeri,  showing  the  microscopic 
structure.  Greatly  enlarged.  Trias. 


Fig.  150.— a,  Skull  of  La- 
byrinthodon  Jcegeri,  much 
reduced  in  size  ;  6,  Tooth 
of  the  same,  Trias,  Wurt- 
temberg. 


was  found  many  years  ago  in  sandstones  near  Elgin,  in  Scot- 
land, and  which  excited  special  interest  at  the  time  in  conse- 
quence of  the  fact  that  the  strata  in  question  were  believed  to 


224  HISTORICAL  PALAEONTOLOGY. 

belong  to  the  Old  Red  Sandstone  formation.  It  is,  however, 
now  certain  that  the  Elgin  sandstones  which  contain  Telerpeton 
Elginense,  as  this  reptile  is  termed,  are  really  to  be  regarded  as 
of  Triassic  age.  By  Professor  Huxley,  Telerpeton  is  regarded 
as  a  Lizard,  which  cannot  be  considered  as  "  in  any  sense 
a  less  perfectly-organized  creature  than  the  Gecko,  whose 
swift  and  noiseless  run  over  walls  and  ceilings  surprises  the 
traveler  in  climates  warmer  than  our  own. "  The  "  Elgin  Sand- 
stones "  have  also  yielded  another  Lizard,  which  was  originally 
described  by  Professor  Huxley  under  the  name  of  Hyperoda- 
pedon,  the  remains  of  the  same  genus  having  been  subsequently 
discovered  in  Triassic  strata  in  India  and  South  Africa.  The 
Lizards  of  this  group  must  therefore  have  at  one  time  enjoyed 
a  very  wide  distribution  over  the  globe;  and  the  living  Spheno- 
don  of  New  Zealand  is  believed  by  Professor  Huxley  to  be  the 
nearest  living  ally  of  this  family.  The  Hyperodapedon  of  the 
Elgin  Sandstones  was  about  six  feet  in  length,  with  limbs 
adapted  for  terrestrial  progression,  but  with  the  bodies  of  the 
vertebrae  slightly  biconcave,  and  having  two  rows  of  palatal 
teeth,  which  become  worn  down  to  the  bone  in  old  age. 
Lastly,  the  curious  Rhynchosaurus  of  the  Trias  is  also  referred, 
by  the  eminent  comparative  anatomist  above  mentioned,  to  the 
order  of  the  Lizards.  In  this  singular  reptile  (fig.  151)  the  skull 

is  somewhat  bird-like,  and  the 
jaws  appear  to  have  been  desti- 
tute of  teeth,  and  to  have  been 
encased  in  a  horny  sheath  like 
the  beak  of  a  Turtle  or  a  Bird. 
It  is  possible,  however,  that  the 
palate  was  furnished  with  teeth. 
Fig.  I5i.-Staiuof  Bhyncho^auru*  arti-  The  group  of  the  Crocodiles 

and     Alligators      (Crocodilia}, 

distinguished  by  the  fact  that  the  teeth  are  implanted  in  dis- 
tinct sockets  and  the  skin  more  or  less  extensively  provided 
with  bony  plates,  is  represented  in  the  Triassic  rocks  by  the 
Stagonolepis  of  the  Elgin  Sandstones.  The  so-called  "  Theco- 
dont"  reptiles  (such  as  Belodon,  Thecodontosaurus,  and  Palao- 
saurus,  fig  152,  c,  d,  e)  are  also  nearly  related  to  the  Croco- 
diles, though  it  is  doubtful  if  they  should  be  absolutely  referred 
to  this  group.  In  these  reptiles,  the  teeth  .are  implanted  in 
distinct  sockets  in  the  jaws,  their  crowns  being  more  or  less 
compressed  and  pointed,  "with  trenchant  and  finely  serrate 
margins"  (Owen).  The  bodies  of  the  vertebrae  are  hollowed 


THE  TRIASSIC  PERIOD. 


225 


out  at  both  ends,  but  the  limbs  appear  to  be  adapted  for  pro- 
gression on  the  land.  The  genus  Belodon  (fig.  152,  c)  is 
known  to  occur  in  the  Keuper  of  Germany  and  in  America; 
and  Palaosaurus  (fig.  153,  e)  has  also  been  found  in  the  Trias 
of  the  same  region.  Teeth  of  the  latter,  however,  are  found, 
along  with  remains  of  Thecodontosaurus  (fig.  153,  d),  in  a 
singular  magnesian  conglomerate  near  Bristol,  which  was 
originally  believed  to  be  of  Permian  age,  but  which  appears 
to  be  undoubtedly  Triassic. 

The  Trias  has  also  yielded  the  remains  of  the  great  marine 
reptiles  which  are  often  spoken  of  collectively  as  the  "  Enalio- 
saurians  "  or  "  Sea-lizards, "  and  which  will  be  more  particularly 
spoken  of  in  treating  of  the  Jurassic  period,  of  which  they  are 
more  especially  characteristic.  In  all  these  reptiles  the  limbs 
are  flattened  out,  the  digits  being  enclosed  in  a  continuous 
skin,  thus  forming  powerful  swimming-paddles,  resembling  the 
"  flippers "  of  the  Whales  and  Dolphins  both  in  their  general 
structure  and  in  function.  The  tail  is  also  long,  and  adapted 
to  act  as  a  swimming-organ ;  and  there  can  be  no  doubt  but 
that  these  extraordinary  and  often  colossal  reptiles  frequented 
the  sea,  and  only  occasionally  came  to  the  land.  The  Triassic 
Enaliosaurs  belong  to  a  group  of  which  the  later  genus 
Plesiosaurus  is  the  type  (the  Sauropterygia}.  One  of  the  best 
known  of  the  Triassic  genera  is  Nothosaurus  (fig.  152,  a),  in 
which  the  neck  was  long  and  bird-like,  the  jaws  being  im- 


Fig.  152.— Triassic  Reptiles,  a.  Skull  of  Nothosaurus  mirabttis,  reduced  in  size— 
Muschelkalk,  Germany  ;  b,  Tooth  of  Simomurus  Gaillardoti,  of  the  natural  size— 
Muschelkalk,  Germany ;  c.  Tooth  of  Belodon  Carohnensis—Trlas,  America  ;  d,  Tooth 
of  Thecodontotaurua  antiquus,  slightly  enlarged— Britain  ;  e,  Tooth  of  Palceo»auru» 
platyodon,  of  the  natural  size — Britain. 

mensely    elongated,    and    carrying    numerous    powerful    conical 
teeth  implanted  in  distinct  sockets.     The  teeth  in  Simosaurus 
15 


226  HISTORICAL  PALAEONTOLOGY. 

(152,  b)  are  of  a  similar  nature;  but  the  orbits  are  of  enormous 
size,  indicating  eyes  of  corresponding  dimensions,  and  perhaps 
pointing  to  the  nocturnal  habits  of  the  animal.  In  the  singular 
Placodus,  again,  the  teeth  are  in  distinct  sockets,  but  resemble 
those  of  many  fishes  in  being  rounded  and  obtuse  (fig.  153), 

forming  broad  crushing  plates 
adapted  for  the  comminu- 
tion of  shell-fish.  There  is  a 
row  of  these  teeth  all  round 
the  upper  jaw  proper,  and  a 
double  series  on  the  palate, 
but  the  lower  jaw  has  only  a 
single  row  of  teeth.  Placodus 
is  found  in  the  Muschelkalk, 
and  the  characters  of  its  den- 
tal apparatus  indicate  that 

Fig.  153.-Under  surface  of  the  upper  !t  was  much  more  Peaceful 
jaw  and  palate  of  Piacodua  gigaa.  Mus-  in  its  habits  than  its  asso- 
cholkalk,  Germany.  .  .  ,,  .  j  c" 

ciates  the   Nothosaur  and  Si- 

mosaur. 

The  Triassic  rocks  of  South  Africa  and  India  have  yielded 
the  remains  of  some  extraordinary  Reptiles,  which  have  been 
placed  by  Professor  Owen  in  a  separate  order  under  the  name 
of  Anomodontia.  The  two  principal  genera  of  this  group  are 
Dicynodon  and  Oudenodon,  both  of  which  appear  to  have  been 
large  Reptiles,  with  well-developed  limbs,  organized  for  pro- 
gression upon  the  dry  land.  In  Oudenodon  (fig.  154,  B)  the 
jaws  seem  to  have  been  wholly  destitute  of  teeth,  and  must 
have  been  encased  in  a  horny  sheath,  similar  to  that  with 
which  we  are  familiar  in  the  beak  of  a  Turtle.  In  Dicynodon 
(fig.  154,  A),  on  the  other  hand,  the  front  of  the  upper  jaw 
and  the  whole  of  the  lower  jaw  were  destitute  of  teeth,  and 
the  front  of  the  mouth  must  have  constituted  a  kind  of  beak; 
but  the  upper  jaw  possessed  on  each  side  a  single  huge  conical 
tusk,  which  is  directed  downwards,  and  must  have  continued 
to  grow  during  the  life  of  the  animal. 

It  may  be  mentioned  that  the  above-mentioned  Triassic 
sandstones  of  South  Africa  have  recently  yielded  to  the  re- 
searches of  Professor  Owen  a  new  and  unexpected  type  of 
Reptile,  which  exhibits  some  of  the  structural  peculiarities 
which  we  have  been  accustomed  to  regard  as  characteristic 
of  the  Carnivorous  quadrupeds.  The  Reptile  in  question  has 
been  named  Cynodraco,  and  it  is  looked  upon  by  its  distin- 


THE  TRIASSIC  PERIOD. 


227 


guished  discoverer  as  the  type  of  a  new  order,  to  which  he  has 
given  the  name  of  Theriodontia.  The  teeth  of  this  singular 
form  agree  with  those  of  the  Carnivorous  quadrupeds  in  con- 
sisting of  three  distinct  groups — namely,  front  teeth  or  incisors, 
eye  teeth  or  canines,  and  back  teeth  or  molars.  The  canines 
also  are  long  and  pointed,  very  much  compressed,  and  having 
their  lateral  margins  finely  serrated,  thus  presenting  a  singular 
resemblance  to  the  teeth  of  the  extinct  "  Sabre-toothed  Tiger " 
(Machairodus} .  The  bone  of  the  upper  arm  (humerus)  further 
shows  some  remarkable  resemblances  to  the  same  bone  in  the 
Carnivorous  Mammals.  As  has  been  previously  noticed,  Pro- 
fessor Owen  is  of  opinion  that  some  of  the  Reptilian  remains 


Fig.  154.— Tr lassie  Anoinodont  Keptiles.  A,  Skull  of  Dieynodon  lacerticeps.  showing 
one  of  the  great  maxillary  tusks  ;  B,  Skull  of  Oudenodon  Bainii,  showing  the  toothless, 
beak- like  jaws.  From  the  Trias  of  South  Africa.  (After  Owen.) 

of  the   Permian  deposits 'will  also  be  found  to  belong  to  this 
group  of  the  "  Theriodonts.  " 

Lastly,  we  find  in  the  Triassic  rocks  the  remains  of  Reptiles 
belonging  to  the  great  Mesozoic  order  of  the  Deinosauria. 
This  order  attains  its  maximum  at  a  later  period,  and  will  be 
spoken  of  when  the  Jurassic  and  Cretaceous  deposits  come  to 
be  considered.  The  chief  interest  of  the  Triassic  Reptiles  of 
this  group  arises  from  the  fact  that  they  are  known  by  their 


228  HISTORICAL  PALEONTOLOGY. 

footprints  as  well  as  by  their  bones;  and  a  question  has  arisen 
whether  the  supposed  footprints  of  birds  which  occur  in  the 
Trias  have  not  really  been  produced  by  Deinosaurs.  This 
leads  us,  therefore,  to  speak  at  the  same  time  as  to  the  evi- 
dence which  we  have  of  the  existence  of  the  class  of  Birds 
during  the  Triassic  period.  No  actual  bones  of  any  bird  have 
as  yet  been  detected  in  any  Triassic  deposit ;  but  we  have 
tolerably  clear  evidence  of  their  existence  at  this  time  in  'he 
form  of  footprints.  The  impressions  in  question  are  found  in 
considerable  numbers  in  certain  red  Sandstones  of  the  age  of 
the  Trias  in  the  valley  of  the  Connecticut  River,  in  the  United 
States.  They  vary  much  in  size,  and  have  evidently  been 
produced  by  many  different  animals  walking  over  long 
stretches  of  estuarine  mud  and  sand  exposed  at  low  water. 
The  footprints  now  under  consideration  form  a  double  series 
of  single  prints,  and  therefore,  beyond  all  question,  are  the 
tracks  of  a  biped — that  is,  of  an  animal  which  walked  upon 


Fig.  155.— Supposed  footprint  of  a  Bird,  from  the  Triassic  Sandstones  of  the  Con- 
necticut River.    The  slab  shows  also  numerous  "rain- prints." 

two  legs.  No  living  animals,  save  Man  and  the  Birds,  walk 
habitually  on  two  legs ;  and  there  is,  therefore,  a  prima  facie 
presumption  that  the  authors  of  these  prints  were  Birds. 
Moreover,  each  impression  consists  of  the  marks  of  three  toes 
turned  forward  (fig.  155),  and  therefore  are  precisely  such  as 
might  be  produced  by  Wading  or  Cursorial  Birds.  Further, 
the  impressions  of  the  toes  show  exactly  the  same  numerical 


THE  TRIASSIC  PERIOD. 


229 


progression  in  the  number  of  the  joints  as  is  observable  in 
living  Birds — that  is  to  say,  the  innermost  of  the  three  toes  con- 
sists of  three  joints,  the  middle  one  of  four,  and  the  outer 
one  of  five  joints.  Taking  this  evidence  collectively,  it  would 
have  seemed,  until  lately,  quite  certain  that  these  tracks  could 
only  have  been  formed  by  Birds.  It  has,  however,  been 
shown  that  the  Deinosaurian  Reptiles  possess,  in  some  cases 
at  any  rate,  some  singularly  bird-like  characters,  amongst 
which  is  the  fact  that  the  animal  possessed  the  power  of 
walking,  temporarily  at  least,  on  its  hind-legs,  which  were 
much  longer  and  stronger  than  the  fore-limbs,  and  which 
were  sometimes  furnished  with  no  more  than  three  toes. 
As  the  bones  and  teeth  of  Deinosaurs  have  been  found  in 
the  Triassic  deposits  of  North  America,  it  may  be  regarded  as 
certain  that  some  of  the  bipedal  tracks  originally  ascribed  to 
Birds  must  have  really  been  produced  by  these  Reptiles.  It 
seems  at  the  same  time  almost  a  certainty  that  others  of  the 
three-toed  impressions  of  the  Connecticut  sandstones  were  in 
truth  produced  by  Birds,  since  it  is  doubtful  if  the  bipedal 
mode  of  progression  was  more  than  an  occasional  thing 
amongst  the  Deinosaurs,  and  the  greater  number  of  the 
many  known  tracks  exhibit  no  impressions  of  fore-feet. 
Upon  the  whole,  therefore,  we  may,  with  much  probability, 
conclude  that  the  great  class  of  Birds  (Aves}  was  in  existence 
in  the  Triassic  period.  If  this  be  so,  not  only  must  there 
have  been  quite  a  number  of  different  forms,  but  some  of 
them  must  have  been  of  very  large  size.  Thus  the  largest 


Fig.  156.— Lower  jaw  of  Dromatherium  sylvestre, 
Trias,  North  Carolina.    (After  Emmons.) 


a 

Fig.  157.— a,  Molar  tooth  of 
Microleates  antiquus,  magni- 
fied ;  6,  Crown  of  the  same, 
magnified  still  further.  Trias, 
Germany. 


footprints  hitherto  discovered  in  the  Connecticut  sandstones 
are  22  inches  long  and  12  inches  wide,  \?ith  a  proportionate 
length  of  stride.  These  measurements  indicate  a  foot  four 
times  as  large  as  that  of  the  African  Ostrich;  and  the  animal 
which  produced  them — whether  a  Bird  or  a  Deinosaur — must 
have  been  of  colossal  dimensions. 


230 


HISTORICAL  PALAEONTOLOGY. 


Finally,  the  Trias  completes  the  tale  of  the  great  classes  of 
the  Vertebrate  sub-kingdom  by  presenting  us  with  remains  of 
the  first  known  of  the  true  Quadrupeds  or  Mammalia.  These 
are  at  present  only  known  by  their  teeth,  or,  in  one  instance, 
by  one  of  the  halves  of  the  lower  jaw;  and  these  indicate 
minute  Quadrupeds,  which  present  greater  affinities  with  the 


Fig.  158.— The  Banded  Ant-eater  (MyrmecoMiis  fasciatua)  of  Australia. 


little  Banded  Ant-eater  (Myrmecobius  fasciatus,  fig.  158)  of 
Australia  than  with  any  other  living  form.  If  this  conjecture 
be  correct,  these  ancient  Mammals  belonged  to  the  order  of 
the  Marsupials  or  Pouched  Quadrupeds  (Marsupialia},  which 
are  now  exclusively  confined  to  the  Australian  province,  South 
America,  and  the  southern  portion  of  North  America.  In 
the  Old  World,  the  only  known  Triassic  Mammals  belong  to 
the  genus  Microlestes,  and  to  the  probably  identical  Hypsi- 
prymnopsis  of  Professor  Boyd  Dawkins.  The  teeth  of  Micro- 
lestes (fig.  157)  were  originally  discovered  by  Plieninger  in 
1847  in  the  "  bone-bed "  which  is  characteristic  of  the  sum- 
mit of  the  Rhaetic  series  both  in  Britain  and  on  the  continent 
of  Europe;  and  the  known  remains  indicate  two  species.  In 
Britain,  teeth  of  Microlestes  have  been  discovered  by  Mr. 
Charles  Moore  in  deposits  of  Upper  Triassic  age,  filling  a 
fissure  in  the  Carboniferous  limestone  near  Frome,  in  Somerset- 
shire; and  a  molar  tooth  of  Hypsiprymnopsis  was  found  by 
Professor  Boyd  Dawkins  in  Rhaetic  marls  below  the  "bone- 
bed,  "  at  Watchet,  also  in  Somersetshire.  In  North  America, 


THE  TRIASSIC  PERIOD.  231 

lastly,  there  has  been  found  in  strata  of  Triassic  age  one  of 
the  branches  of  the  lower  jaw  of  a  small  Mammal,  which  has 
been  described  under  the  name  of  Dromatherium  sylvestre 
(fig.  156).  The  fossil  exhibits  ten  small  molars  placed  side 
by  side,  one  canine,  and  three  incisors,  separated  by  small 
intervals,  and  it  indicates  a  small  insectivorous  animal,  prob- 
ably most  nearly  related  to  the  existing  Myrmecobius. 


LITERATURE. 


The  following  list  comprises  a  few  of  the  more  important 
sources  of  information  as  to  the  Triassic  strata  and  their  fossil 
contents : — 

(1)  'Geology  of   Oxford   and   the   Valley   of   the   Thames.' 

Phillips. 

(2)  '  Memoirs  of  the  Geological  Survey  of  Great  Britain  and 

Ireland. ' 

(3)  '  Report  on  the  Geology  of  Londonderry, '  &c.    Portlock. 

(4)  "  On  the  Zone  of  Avicula  contorta, "  &c. — '  Quart.  Journ. 

Geol.  Soc., '  vol.  xvi.,  1860.     Dr.  Thomas  Wright. 

(5)  "  On  the  Zones  of  the  Lower  Lias  and  the  Avicula  con- 

torta Zone  " — '  Quart.  Journ.  Geol.  Soc., '  vol.  xvii.,  1861. 
Charles  Moore. 

(6)  "  On  Abnormal  Conditions  of  Secondary  Deposits, "  &c. 

— '  Quart.  Journ.  Geol.  Soc., '  vol.  xxiii.,  1876-77.  Charles 
Moore. 

(7)  '  Geognostische   Beschreibung  des   Bayerischen   Alpenge- 

birges. '     Giimbel. 

(8)  'Lethaea  Rossica. '     Pander. 

(9)  '  Lethaea  Geognostica. '     Bronn. 

(10)  '  Petrefacta  Germaniae. '    Goldfuss. 
(n)  '  Petrefaktenkunde. '     Quenstedt. 

(12)  'Monograph  of  the  Fossil  Estheriae'  ( Palaeontographical 

Society).    Rupert  Jones. 

(13)  "Fossil    Remains    of    Three    Distinct    Saurian    Animals, 

recently  discovered  in  the  Magnesian  Conglomerate 
near  Bristol "-  -'  Trans.  Geol.  Soc., '  ser.  2,  vol.  v.,  1840. 
Riley  and  Stutchbury. 

(14)  'Die  Saurier  des  Muschelkalkes. '    Von  Meyer. 

(15)  '  Beitrage      zur      Palasontologie      Wiirttembergs. '      Von 

Meyer  and  Plieninger. 

(16)  'Manual  of  Palaeontology.'     Owen. 

(17)  '  Odontography. '     Owen. 

(18)  'Report  of  Fossil  Reptiles'   (British  Association,  1841). 

Owen. 


232  HISTORICAL  PALEONTOLOGY. 

(19)  "On    Dicynodon" — 'Trans.    Geol.    Soc., '    vol.    Hi.,    1845. 

Owen. 

(20)  '  Descriptive  Catalogue  of  Fossil  Reptilia  and  Fishes  in 
the   Museum  of  the  Royal   College  of   Surgeons,   Eng- 
land. '     Owen. 

(21 )  "  On   Species  of  Labyrinthodon   from   Warwickshire " — 

'Trans.  Geol.  Soc., '  ser.  2,  vol.  vi.    Owen. 

(22)  "On  a  Carnivorous  Reptile"   (Cynodraco  major),  &c. — 

'  Quart.  Journ.  Geol.  Soc., '  vol.  xxxii.,  1876.     Owen. 

(23)  "On   Evidences   of   Theriodonts   in    Permian   Deposits," 
&c. — '  Quart.  Journ.  Geol  Soc., '  vol.  xxxii.,  1876.     Owen. 

(24)  "  On  the  Stagonolepis  Robertsoni, "  &c. — '  Quart.  Journ. 

Geol.  Soc., '  vol.  xv.,  1859.     Huxley. 

(25)  "On     a     New     Specimen     of     Telerpeton     Elginense " — 

'Quart.  Journ.  Geol.  Soc., '  vol.  xxiii.,  1866.     Huxley. 

(26)  "  On  Hyperodapedon  " — '  Quart.  Journ.  Geol.  Soc., '  vol. 
xxv.,   1869.     Huxley. 

(27)  "  On    the    Affinities    between    the    Deinosaurian    Reptiles 

and  Birds  " — '  Quart.  Journ.  Geol.  Soc., '  vol  xxvi.,  1870. 
Huxley. 

(28)  "  On     the     Classification     of     the     Deinosauria. "     &c. — 

*  Quart.  Journ.  Geol.  Soc., '  vol.  xxvi.,  1870.     Huxley. 

(29)  "  Patoeontologica   Indica  " — '  Memoirs   of   the   Geol.    Sur- 

vey of  India. ' 

(30)  "  On  the  Geological  Position  and  Geographical  Distribu- 
tion of  the  Dolomitic  Conglomerate  of  the  Bristol  Area  " 
— '  Quart.  Journ.  Geol.  Soc., '  vol.  xxvi.,  1870.     R.  Ethe- 
ridge,  sen. 

(31)  "Remains  of  Labyrinthodonta   from  the  Keuper   Sand- 

stone   of   Warwick " — '  Quart.    Journ.    Geol.    Soc., '   vol. 
xxx.,  1874.     Miall. 

(32)  '  Manual  of  Geology. '     Dana. 

(33)  '  Synopsis  of   Extinct  Batrachia  and  Reptilia  of   North 

America. '     Cope. 

(34)  '  Fossil  Footmarks. '     Hitchcock. 

(35)  '  Ichnology  of  New  England.'     Hitchcock. 

(36)  '  Traite  de  Paleontologie  Vegetale. '     Schimper. 

(37)  '  Histoire  des  Vegetaux  Fossiles. '     Brongniart. 

(38)  '  Monographic  der  Fossilen  Coniferen. '     Goeppert. 


CHAPTER  XVI. 

THE  JURASSIC  PERIOD. 

Resting  upon  the  Trias,  with  perfect  conformity,  and  with 
an  almost  undeterminable  junction,  we  have  the  great  series  of 


THE  JURASSIC  PERIOD.  233 

deposits  which  are  known  as  the  Oolitic  Rocks,  from  the  com- 
mon occurrence  in  them  of  oolitic  limestones,  or  as  the  Juras- 
sic Rocks,  from  their  being  largely  developed  in  the  mountain- 
range  of  the  Jura,  on  the  western  borders  of  Switzerland. 
Sediments  of  this  series  occupy  extensive  areas  in  Great  Britain, 
on  the  continent  of  Europe,  and  in  India.  In  North  America, 
limestones  and  marls  of  this  age  have  been  detected  in  "  the 
Black  Hills,  the  Laramie  range,  and  other  eastern  ridges  of  the 
Rocky  Mountains ;  also  over  the  Pacific  slope,  in  the  Uintah, 
Wahsatch,  and  Humboldt  Mountains,  and  in  the  Sierra  Ne- 
vada" (Dana);  but  in  these  regions  their  extent  is  still  un- 
known, and  their  precise  subdivisions  have  not  been  deter- 
mined. Strata  belonging  to  the  Jurassic  period  are  also  known 
to  occur  in  South  America,  in  Austrafia,  and  in  the  Arctic 
zone.  When  fully  developed,  the  Jurassic  series  is  capable  of 
subdivision  into  a  number  of  minor  groups,  of  which  some  are 
clearly  distinguished  by  their  mineral  characters,  whilst  others 
are  separated  with  equal  certainty  by  the  differences  of  the 
fossils  that  they  contain.  It  will  be  sufficient  for  our  present 
purpose,  without  entering  into  the  more  minute  subdivisions 
of  the  series,  to  give  here  a  very  brief  and  general  account 
of  the  main  sub-groups  of  the  Jurassic  rocks,  as  developed  in 
Britain — the  arrangement  of  the  Jura-formation  of  the  continent 
of  Europe  agreeing  in  the  main  with  that  of  England. 

I.  THE  LIAS. — The  base  of  the  Jurassic  series  of  Britain 
is  formed  by  the  great  calcareo-argillaceous  deposit  of  the 
"  Lias, "  which  usually  rests  conformably  and  almost  inseparably 
upon  the  Rhaetic  beds  (the  so-called  "White  Lias"),  and 
passes  up,  generally  conformably,  into  the  calcareous  sand- 
stones of  the  Inferior  Oolite.  The  Lias  is  divisible  into  the 
three  principal  groups  of  the  Lower,  Middle,  and  Upper  Lias, 
as  below,  and  these  in  turn  contain  many  well-marked  "  zones ;  " 
so  that  the  Lias  has  some  claims  to  be  considered  as  an  inde- 
pendent formation,  equivalent  to  all  the  remaining  Oolitic 
rocks.  The  Lower  Lias  (Terrain  Sinemurien  of  D'Orbigny) 
sometimes  attains  a  thickness  of  as  much  as  600  feet,  and  con- 
sists of  a  great  series  of  bluish  or  greyish  laminated  clays, 
alternating  with  thin  bands  of  blue  or  grey  limestone — the 
whole,  when  seen  in  quarries  or  cliffs  from  a  little  distance, 
assuming  a  characteristically  striped  and  banded  appearance. 
By  means  of  particular  species  of  Ammonites,  taken  along  with 
other  fossils  which  are  confined  to  particular  zones,  the  Lower 
Lias  may  be  subdivided  into  several  well-marked  horizons. 


234  HISTORICAL  PALEONTOLOGY. 

The  Middle  Lias,  or  Marlstone  Series  (Terrain  Liasien  of 
D'Orbigny),  may  reach  a  thickness  of  200  feet,  and  consists  of 
sands,  arenaceous  marls,  and  argillaceous  limestones,  sometimes 
with  ferruginous  beds.  The  Upper  Lias  (Terrain  Toarcien  of 
D'Orbigny)  attains  a  thickness  of  300  feet,  and  consists  princi- 
pally of  shales  below,  passing  upwards  into  arenaceous  strata. 

II.  THE   LOWER    OOLITES.— Above    the    Lias    comes    a    com- 
plex   series    of    partly    arenaceous    and    argillaceous,    but    prin- 
cipally calcareous  strata,  of  which  the  following  are  the  more 
important    groups:    a,    the    Inferior    Oolite    (Terrain    Bajocien 
of    D'Orbigny),    consisting    of    more    than    200    feet    of    oolitic 
limestones,    sometimes    more    or    less    sandy;    b,    The    Fuller's 
Earth,  a  series  of  shales,   clays,   and  marls,   about   120  feet   in 
thickness;  c,  The  Great  Oolite  or  Bath  Oolite   (Terrain  Bath- 
onien    of    D'Orbigny),    consisting    principally    of    oolitic    lime- 
stones, and  attaining  a  thickness  of  about  130  feet.     The  well- 
known    "  Stonesfield    Slates "   belong   to   this   horizon ;    and   the 
locally  developed  "  Bradford   Clay,  "   "  Cornbrash,  "   and   "  For- 
est-marble "    may   be    regarded   as    constituting   the    summit    of 
this  group. 

III.  THE    MIDDLE    OOLITES. — The    central    portion    of    the 
Jurassic  series  of  Britain  is   formed  by  great  argillaceous   de- 
posit, capped  by  calcareous  strata,  as  follows :  a,   The  Oxford 
Clay  (Terrain  Callovien  and  Terrain  Oxjordien  of  D'Orbigny), 
consisting    of    dark-colored    laminated    clays,    sometimes    reach- 
ing a  thickness  of  700  feet,  and  in  places  having  its  lower  por- 
tion   developed    into    a    hard    calcareous    sandstone    ("Kelloway 
Rock");    b,   The    Coral-Rag    (Terrain   Corallien   of    D'Orbigny, 
"  Nerinean    Limestone "    of   the   Jura,    "  Diceras    Limestone "    of 
the    Alps),    consisting,    when    typically    developed,    of    a    central 
mass   of   oolitic    limestone,    underlaid   and    surmounted   by   cal- 
careous grits. 

IV.  THE    UPPER     OOLITES. — a,    The    base     of     the     Upper 
Oolites  of  Britain  is  constituted  by  a  great  thickness    (600  feet 
or  more)    of  laminated,  sometimes  carbonaceous  or  bituminous 
clays,  which  are  known  as  the  Kimmeridge  Clay   (Terrain  Kim- 
meridgien  of  D'Orbigny)  ;  b,  The  Portland  Beds  (Terrain  Port- 
landien  of  D'Orbigny)    succeed  the  Kimmeridge  clay,  and  con- 
sist inferiorly  of   sandy  beds   surmounted  by  oolitic   limestones 
("Portland  Stone"),  the  whole  series  attaining  a  thickness  of 
150  feet  or  more,  and  containing  marine  fossils;   c,  The  Pur- 
beck  Beds  are  apparently  peculiar  to  Great  Britain,  where  they 
form  the  summit  of  the  entire  Oolitic  series,  attaining  a  total 


THE  JURASSIC  PERIOD.  235 

thickness  of  from  150  to  200  feet.  The  Purbeck  beds  consist 
of  arenaceous,  argillaceous,  and  calcareous  strata,  which  can 
be  shown  by  their  fossils  to  consist  of  a  most  remarkable  alter- 
nation of  fresh-water,  brackish-water,  and  purely  marine  sedi- 
ments, together  with  old  land-surfaces,  or  vegetable  soils,  which 
contain  the  upright  stems  of  trees,  and  are  locally  known  as 
"  Dirt-beds. " 

One  of  the  most  important  of  the  Jurassic  deposits  of  the 
continent  of  Europe,  which  is  believed  to  be  on  the  horizon 
of  the  Coral-rag  or  of  the  lower  part  of  the  Upper  Oolites,  is 
the  "  Solenhofeu  Slate  "  of  Bavaria,  an  exceedingly  fine-grained 
limestone,  which  is  largely  used  in  lithography,  and  is  cele- 
brated for  the  number  and  beauty  of  its  organic  remains,  and 
especially  for  those  of  Vertebrate  animals. 

The  subjoined  sketch-section  (fig.  159)  exhibits  in  a  dia- 
grammatic form  the  general  succession  of  the  Jurassic  rocks  of 
Britain. 

Regarded  as  a  whole,  the  Jurassic  formation  is  essentially 
marine ;  and  though  remains  of  drifted  plants,  and  of  insects 
and  other  air-breathing  animals,  are  not  uncommon,  the  fossils 
of  the  formation  are  in  the  main  marine.  In  the  Purbeck 
series  of  Britain,  anticipatory  of  the  great  .river-deppsit  of  the 
Wealden,  there  are  fresh-water,  brackish-water,  and  even  terres- 
trial strata,  indicating  that  the  floor  of  the  oolitic  ocean  was 
undergoing  upheaval,  and  that  the  marine  conditions  which 
had  formerly  prevailed  were  nearly  at  an  end.  In  places 
also,  as  in  Yorkshire  and  Sutherlandshire,  are  found  actual 
beds  of  coal :  but  the  great  bulk  of  the  formation  is  an  indu- 
bitable sea-deposit;  and  its  limestones,  oolitic  as  they  com- 
monly are,  nevertheless  are  composed  largely  of  the  commin- 
uted skeletons  of  marine  animals.  Owing  to  the  enormous 
number  and  variety  of  the  organic  remains  which  have  been 
yielded  by  the  richly  fossiliferous  strata  of  the  Oolitic  series, 
it  will  not  be  possible  here  to  do  more  than  to  give  an  outline- 
sketch  of  the  principal  forms  of  life  which  characterize  the 
Jurassic  period  as  a  whole.  It  is  to  be  remembered,  however, 
that  every  minor  group  of  the  Jurassic  formation  has  its  own 
peculiar  fossils,  and  that  by  the  labors  of  such  eminent  ob- 
servers as  Quenstedt,  Oppel,  D'Orbigny,  Wright,  De  la  Beche, 
Tate,  and  others,  the  entire  series  of  Jurassic  sediments  admits 
of  a  more  complete  and  more  elaborate  subdivision  into  zones 
characterized  by  special  life-forms  than  has  as  yet  been  found 
practicable  in  the  case  of  any  other  rock-series. 


HISTORICAL  PALAEONTOLOGY. 


GENERALIZED  SECTION  OF  THE  JURASSIC  ROCKS 
OF  ENGLAND. 


Fig.  159- 


—  Purbeck  Beds. 
—-  Portland   Beds. 


Kimmeridge  Clay. 


Coral -Rag. 


Oxford  Clay. 

5  Cornbrash  and  Forest- 
l      marble. 
Great  Oolite. 

Fuller's   Earth. 
Inferior  Oolite. 

Upper  Lias. 


Middle     Lias     (Marl- 
stone  series). 


Lower  Lias. 

J  Rhsetic   Marls  ("  White 
I     Lias"). 


The  plants  of  the  Jurassic  period  consist  principally  of 
Ferns,  Cycads,  and  Conifers — agreeing  in  this  respect,  there- 
fore, with  those  of  the  preceding  Triassic  formation.  The 
Ferns  are  very  abundant,  and  belong  partly  to  old  and  partly 
to  new  genera.  The  Cycads  are  also  very  abundant,  and,  on 


THE  JURASSIC  PERIOD.  237 

/ 

the  whole,  constitute  the  most  marked  feature  of  the  Jurassic 
vegetation,  many  genera  of  this  group  being  known  (Ptero- 
phyllum,  Otozamites,  Zamites,  Crossozamia,  Williamsonia,  Buck- 
landia,  &c.)  The  so-called  "dirt-bed"  of  the  Purbeck  series 
consists  of  an  ancient  soil,  in  which  stand  erect  the  trunks  of 
Conifers  and  the  silicified  stools  of  Cycads  of  the  genus  Mantel- 
lia  (fig.  160).  The  Co-nifera  of  the  Jurassic  are  represented  by 
various  forms  more  or  less  nearly  allied  to  the  existing  Arau- 
carice;  and  these  are  known  not  only  by  their  stems  or 
branches,  but  also  in  some  cases  by  their  cones.  We  meet, 
also,  with  the  remains  of  undoubted  Endogenous  plants,  the 
most  important  of  which  are  the  fruits  of  forms  allied  to  the 
existing  Screw-pines  (Pandanece},  such  as  Podocarya  and  Kaida- 
carpum.  So  far,  however,  no  remains  of  Palms  have  been 
found;  nor  are  we  acquainted  with  any  Jurassic  plants  which 
could  be  certainly  referred  to  the  great  "  Angiospermous " 
group  of  the  Exogens,  including  the  majority  of  our  ordinary 
plants  and  trees. 

Amongst  animals,  the  Protozoans  are  well  represented  in 
the  Jurassic  deposits  by  numerous  Foraminifers  and  Sponges; 
as  are  the  Coclenterates  by  numerous  Corals,  Remains 


Fig.  160.— Mantellia  (Cycadeoidea)  megalophylla,  a  Cycad  from  the  Purbeck 
"dirt-bed."    Upper  Oolites,  England. 

of  these  last-mentioned  organisms  are  extremely  abundant 
in  some  of  the  limestones  of  the  formation,  such  as  the 
"  Coral-rag "  and  the  Great  Oolite ;  and  the  former  of  these 
may  fairly  be  considered  as  an  ancient  "  reef. "  The  Rugose 
Corals  have  not  hitherto  been  detected  in  the  Jurassic  rocks; 
and  the  "  Tabulate  Corals, "  so-called,  are  represented  only  by 
examples  of  the  modern  genus  Millepora.  With  this  excep- 
tion, all  the  Jurassic  Corals  belonging  to  the  great  group  which 
predominates  in  recent  seas  (Zoantharia  sclerodermata)  ;  and 


238  HISTORICAL  PALAEONTOLOGY. 

the  majority  belong  to  the  important  reef -building  family  of 
the  "Star-corals"  (Astrccida) .  The  form  here  figured  (Thecos- 
milia  annularis,  fig.  161)  is  one  of  the  characteristic  species 
of  the  Coral-rag. 

The  Echinoderms  are  very  numerous  and  abundant  fossils 
in  the  Jurassic  series,  and  are  represented  by  Sea-lilies,  Sea- 
urchins,  Star-fishes,  and  Brittle-stars.  The  Crinoids  are  still 
common,  and  some  of  the  limestones  of  the  series  are  largely 
composed  of  the  debris  of  these  organisms.  Most  of  the 
Jurassic  forms  resemble  those  with  which  we  are  already 
familiar,  in  having  the  body  permanently  attached  to  some 
foreign  object  by  means  of  a  longer  or  shorter  jointed  stalk 


Fig.  161. — Tkecosmilia  annularis.    Coral-rag,  England. 

or  "  column. "  One  of  the  most  characteristic  Jurassic  genera 
of  these  "  stalked "  Crinoids  (though  not  exclusively  confined 
io  this  period)  is  Pentacrinus  (fig.  162).  In  this  genus,  the 
column  is  five-sided,  with  whorls  of  "  side-arms ;  "  and  the  arms 
are  long,  slender,  and  branched.  The  genus  is  represented 
at  the  present  day  by  the  beautiful  "  Medusa-head  Pentacrin- 
ite"  (Pentacrinus  caput-medusa).  Another  characteristic  Oolitic 
genus  is  Apiocrinus,  comprising  the  so-called  "  Pear  Encrinites.  " 
In  this  group  the  column  is  long  and  rounded,  with  a  dilated 
base,  and  having  its  uppermost  joints  expanded  so  as  to  form, 
with  the  cup  itself,  a  pear-shaped  mass,  from  the  summit  of 
which  spring  the  comparatively  short  arms.  Besides  the 


THE  JURASSIC  PERIOD.  239 

"  stalked "    Crinoids,    the    Jurassic    rocks    have    yielded   the    re- 
mains  of   the  higher   group   of   the   "  free "    Crinoids,   such   as 


Fig.  162.— Pentacrinusfaaciculoaw,  Lias.  The  left-hand  figure  shows  a  few  of  the 
joints  of  the  column  ;  the  middle  figure  shows  the  arms,  and  the  summit  of  the  column 
with  its  side-arms  ;  and  the  right-hand  figure  shows  the  articulating  surface  of  one  of 
the  column-joints. 

Saccosoma.      These    forms    resemble    the    existing    "  Feather- 
stars"    (Comatula)    in    being    attached    when    young    to    some 


240  HISTORICAL  PALAEONTOLOGY. 

foreign  body  by  means  of  a  jointed  stem,  from  which  they 
detach  themselves  when  fully  grown  to  lead  an  independent 
existence.  In  this  later  stage  of  their  life,  therefore,  they 
closely  resemble  the  Brittle-stars  in  appearance.  True  Star- 
fishes (Asteroids)  and  Brittle-stars  (Ophiuroids)  are  abundant 
in  the  Jurassic  rocks,  and  the  Sea-urchins  (Echinoids)  are  so 
numerous  and  so  well  preserved  as  to  constitute  quite  a  marked 
feature  of  some  beds  of  the  series.  All  the  Oolitic  urchins 
agree  with  the  modern  Echinoids  in  having  the  shell  composed 
of  no  more  than  twenty  rows  of  plates.  Many  different  genera 
are  known,  and  a  characteristic  species  of  the  Middle  Oolites 
(Hemicidaris  crenularis,  fig.  163)  is  here  figured. 


Fig.  Wd.—Hemicidaria  crenularis,  showing  the  great  tubercles  on  which  the 
spines  were  supported.    Middle  Oolites. 

Passing  over  the  Annelides,  which,  though  not  uncommon, 
are  of  little  special  interest,  we  come  to  the  Articulates,  which 
also  require  little  notice.  Amongst  the  Crustaceans,  whilst  the 
little  Water-fleas  (Ostracoda)  are  still  abundant,  the  most 
marked  feature  is  the  predominance  which  is  now  assumed  by  the 
Decapods — the  highest  of  the  known  groups  of  the  class.  True 
Crabs  (Brachyura)  are  by  no  means  unknown;  but  the  prin- 
cipal Oolitic  Decapods  belonged  to  the  "  Long-tailed "  group 
(Macrura),  of  which  the  existing  Lobsters,  Prawns,  and 
Shrimps  are  members.  The  fine-grained  lithographic  slates  of 
Solenhofen  are  especially  famous  as  a  depot  for  the  remains 
of  these  Crustaceans,  and  a  characteristic  species  from  this 
locality  (Eryon  arctiformis,  fig.  164)  is  here  represented. 
Amongst  the  air-breathing  Articulates,  we  meet  in  the  Oolitic 
rocks  with  the  remains  of  Spiders  (Arachnids),  Centipedes 
(Myriapoda),  and  numerous  true  Insects  (Insecta),  In  con- 
nection with  the  last-mentioned  of  these  groups,  it  is  of  interest 


THE  JURASSIC  PERIOD. 


241 


to  note  the  occurrence  of  the  oldest  known  fossil  Butterfly 
— the  Palceontina  Oolitica  of  the  Stonesfield  slate — the  rela- 
tionships of  which  appear  to  be  with  some  of  the  living 
Butterflies  of  Tropical  America. 

Coming    to    the    Mollusca,    the    Polyzoans,    numerous    and 


Fig.  164.— Eryon  arctifonuis,  a  "  Long-tailed  Decapod,"  from  the  Middle 
Oolites  (Solenhof en  Slate.) 

beautiful  as  they  are,  must  be  at  once  dismissed;  but  the 
Brachiopods  deserve  a  moment's  attention.  The  Jurassic 
Lamp-shells  (fig.  165)  do  not  fill  by  any  means  such  a  pre- 
dominant place  in  the  marine  fauna  of  the  period,  as  in  many 
Palaeozoic  deposits,  but  they  are  still  individually  numerous. 
The  two  ancient  genera  Left  tana  (fig.  165,  a)  and  Spirifera  (fig. 
165,  fc),  dating  the  one  from  the  Lower  and  the  other  from  the 
Upper  Silurian,  appear  here  for  the  last  time  upon  the  scene, 
but  they  have  not  hitherto  been  recognized  in  deposits  later 
than  the  Lias.  The  great  majority  of  the  Jurassic  Brachiopods, 
however,  belong  to  the  genera  Terebratula  (fig.  165  c,  e,  /) 
and  Rhynchonella  (fig.  165,  d},  both  of  which  are  represented 
by  living  forms  at  the  present  day.  The  Terebratula,  in  par- 
16 


242 


HISTORICAL  PALEONTOLOGY. 


ticular,  are  very  abundant,  and  the  species  are  often  confined 
to  special  horizons  in  the  series. 

Remains  of  Bivalves  (Lamcllibranchiata}  are  very  numerous 
in  the  Jurassic  deposits,  and  in  many  cases  highly  character- 
istic. In  the  marine  beds  of  the  Oolites,  which  constitute  by 
far  the  greater  portion  of  the  whole  formation,  the  Bivalves 
are  of  course  marine,  and  belong  to  such  genera  as  Trigonia, 
Lima,  Pholadomya,  Cardinia,  Avicula,  Hippo  podium,  &c. ;  but 
in  the  Purbeck  beds,  at  the  summit  of  the  series,  we  find 
bands  of  Oysters  alternating  with  strata  containing  fresh-water 
or  brackish-water  Bivalves,  such  as  Cyrcncc  and  Corbula.  The 
predominant  Bivalves  of  the  Jurassic,  however,  are  the  Oysters, 


Fig.  165. — Jurassic  Brachiopods.  «,  Lept&na  Liasaica,  enlarged,  the  small  cross  be- 
low the  figure  indicating  the  true  size  of  the  shell— Lias,  b,  Spirifera  rostrata,  Lias  ;  c, 
Terebratula  quadrifida,  Lias  ;  d,  d',  Rhynchonella  varians,  Fuller's  Earth  and  Kello- 
way  Rock  ;  e.  Terebratula  spficeroidalis,  Inferior  Oolite  ;  /,  Terebratula  dlgona,  Brad- 
ford Clay,  Forest- marble,  and  Great  Oolite.  (After  Davidson). 

which  occur  under  many  forms,  and  often  in  vast  numbers, 
particular  species  being  commonly  restricted  to  particular 
horizons.  Thus  of  the  true  Oysters,  Ostrea  distorta  is  char- 
acteristic of  the  Purbeck  series,  where  it  forms  a  bed  twelve 
feet  in  thickness,  known  locally  as  the  "  Cinder-bed ;  "  Ostrea 
expansa  abounds  in  the  Portland  beds;  Ostrea  deltoidea  is 
characteristic  of  the  Kimmeridge  clay ;  Ostrea  gregaria  pre- 
dominates in  the  Coral-rag;  Ostrea  acuminata  characterizes  the 
small  group  of  the  Fuller's  Earth;  whilst  the  plaited  Ostrea 


THE  JURASSIC  PERIOD. 


243 


Marshii  (fig.  166)  is  a  common  shell  in  the  Lower  and  Middle 
Oolites.  Besides  the  more  typical  Oysters,  the  Oolitic  rocks 
abound  in  examples  of  the  singularly  unsymmetrical  forms 
belonging  to  the  genera  Exogyra  and  Gryphaa  (fig.  167).  In 
the  former  of  these  are  included  Oysters  with  the  beaks 
"  reversed  " — that  is  to  say,  turned  towards  the  hinder  part  of 
the  shell;  whilst  in  the  latter  are  Oysters  in  which  the  lower 
valve  of  the  shell  is  much  the  largest,  and  has  a  large  incurved 
beak,  whilst  the  upper  valve  is  small  and  concave.  One  of 
the  most  characteristic  Exogyra  is  the  E.  Virgula  of  the  Oxford 
Clay,  and  of  the  same  horizon  on  the  Continent;  and  the 
Gryphaa  incurva  (fig.  167)  is  equally  abundant  in,  and  char- 
acteristic of,  the  formation  of  the  Lias.  Lastly,  we  may 


Fig.  166.— Ostrea  Marshii.    Middle 
and  Lower  Oolites. 


Fig.  167. — Gryphcea  incurva.    Lias. 


notice  the  extraordinary  shells  belonging  to   the  genus  Diceras 
(fig.     168),     which     are     exclusively    confined     to     the     Middle 

Oolites.  In  this  formation  in 
the  Alps  they  occur  in  such 
abundance  as  to  give  rise  to 
the  name  of  "  Calcaire  a  Di- 
cerates, "  applied  to  beds  of 
the  same  age  as  the  Coral- 
rag  of  Britain.  The  genus  Di- 
ceras belongs  to  the  same  fam- 
ily as  the  "  Thorny  Clams " 
(Chama)  of  the  present  day — 
the  shell  being  composed  of 

nearly  equally-sized  valves,  the 
Fig.  m.-Dicera^arietina.     Middle         beakg   Qf    whkh    arg    extremely 

prominent   and   twisted   into   a 

spiral.     The   shell  was   attached  to   some   foreign   body  by  the 
l:eak  of  one  of  its  valves. 


244 


HISTORICAL  PALEONTOLOGY. 


Amongst  the  Jurassic  Univalves  (Gasteropoda)  there  are 
many  examples  of  the  ancient  and  long-lived  Pleurotomaria; 
but  on  the  whole  the  Univalves  begin  to  have  a  modern 
aspect.  The  round-mouthed  ("  holostomatous "),  vegetable- 
eating  Sea-snails,  such  as  the  Limpets  (Patellidcc),  the  Nerites 
(Nerita),  the  Turritellcu,  Chemnitzice,  &c.,  still  hold  a  predomi- 
nant place.  The  two  most  noticeable  genera  of  this  group 
are  Cerithium  and  Ner'maa — the  former  of  these  attaining 
great  importance  in  the  Tertiary  and  Recent  seas,  whilst  the 
latter  (fig.  169)  is  highly  characteristic  of  the  Jurassic  series, 
though  not  exclusively  confined  to 
it.  One  of  the  limestones  of  the 
Jura,  believed  to  be  of  the  age  of 
the  Coral-rag  (Middle  Oolite)  of  Bri- 
tain, abounds  to  such  an  extent  in 
the  turreted  shells  of  Nerincea  as  to 
have  gained  the  name  of  "  Calcaire 
a  Nerinees.  "  In  addition  to  forms 
such  as  the  preceding,  we  now  for 
the  first  time  meet,  in  any  force, 
with  the  Carnivorous  -Univalves,  in 
which  the  mouth  of  the  shell  is 
notched  or  produced  into  a  canal, 
giving  rise  to  the  technical  name  Fig.  IGO.  —  Nerincea  Goodhaiiu, 

f     «    .    ,  „  r     ,  one-fourth  of  the  natural  size.    The 

SlpnonostomatOUS,         applied     to    left-hand  figure  shows  the  appear- 

the  shell.  Some  of  the  carnivorous 
forms  belong  to  extinct  types,  such  land, 
as  the  Purpuroidea  of  the  Great  Oo- 
lite; but  others  are  referable  to  well-known  existing  genera. 
Thus  we  meet  here  with  species  of  the  familiar  groups  of  the 
Whelks  (Buccinum),  the  Spindle-shells  (Fusus),  the  Spider- 
shells  (Pteroceras),  Murex,  Rostellaria,  and  others  which  are 
not  at  present  known  to  occur  in  any  earlier  formation. 

Amongst  the  Wing-shells  (Pteropoda),it  is  sufficient  to  mark 
the  final  appearance  in  the  Lias  of  the  ancient  genus  Conularia. 

Lastly,  the  order  of  the  Cephalopoda,  in  both  its  Tetrabran- 
chiate  and  Dibranchiate  sections,  undergoes  a  vast  devel- 
opment in  the  Jurassic  period.  The  old  and  comparatively 
simple  genus  Nautilus  is  still  well  represented,  one  species 
being  very  similar  to  the  living  Pearly  Nautilus  (N.  pompilius)  ; 
but  the  Orthocerata  and  Goniatites  of  the  Trias  have  finally 
disappeared;  and  the  great  majority  of  the  Tetrabranchiate 
forms  are  referable  to  the  comprehensive  genus  Ammonites, 


THE  JURASSIC  PERIOD. 


245 


with  its  many  sub-genera  and  its  hundreds  of  recorded  species. 
The  shell  in  Ammonites  is  in  the  form  of  a  flat  spiral,  all  the 
coils  of  which  are  in  contact  (figs.  170  and  171).  The  inner- 


Fig,  no.— Ammonites  Humphrcaianus .    Inferior  Oolite. 

most  whorls  of  the  shell  are  more  or  less  concealed ;  and  the 
body-chamber  is  elongated  and  narrow,  rather  than  expanded 
towards  the  mouth.  The  tube  or  siphuncle  which  runs  through 
the  air-chambers  is  placed  on  the  dorsal  or  convex  side  of  the 


Fig.  171.— Ammonites  bifrons.    Lias. 

shell ;  but  the  principal  character  which  distinguishes  Ammon- 
ites from  Goniatites  and  Ceratites  is  the  wonderfully  complex 
manner  in  which  the  septa,  or  partitions  between  the  air-cham- 
bers, are  folded  and  undulated.  To  such'  an  extent  does  this 


246  HISTORICAL  PALEONTOLOGY. 

take  place,  that  the  edges  of  the  septa,  when  exposed  by  the 
removal  of  the  shell-substance,  present  in  an  exaggerated  man- 
ner the  appearance  exhibited  by  an  elaborately-dressed  shirt- 
frill  when  viewed  edgewise.  The  species  of  Ammonites  range 
from  the  Carboniferous  to  the  Chalk;  but  they  have  not  been 
found  in  deposits  older  than  the  Secondary,  in  any  region 
except  India;  and  they  are  therefore  to  be  regarded  as  essen- 
tially Mesozoic  fossils.  Within  these  limits,  each  formation 
is  characterized  by  particular  species,  the  number  of  individ- 
uals being  often  very  great,  and  the  size  which  is  sometimes 
attained  being  nothing  short  of  gigantic.  In  the  Lias,  par- 
ticular species  of  Ammonites  may  succeed  one  another  regu- 
larly, each  having  a  more  or  less  definite  horizon,  which  it  does 
not  transgress.  It  is  thus  possible  to  distinguish  a  certain 
number  of  zones,  each  characterized  by  a  particular  Ammonite, 
together  with  other  associated  fossils.  Some  of  these  zones 
are  very  persistent  and  extend  over  very  wide  areas,  thus  af- 
fording valuable  aid  to  the  geologist  in  his  determination  of 
rocks.  It  is  to  be  remembered,  however,  that  there  are  other 
species  which  are  not  thus  restricted  in  their  vertical  range, 
even  in  the  same  formations  in  which  definite  zones  occur. 

The  Cuttle-fishes  or  Dibranchiate  Cephalopods  constitute  a 
feature  in  the  life  of  the  Jurassic  period  little  less  conspicuous 
and  striking  than  that  afforded  by  the  multitudinous  and  varied 
chambered  shells  of  the  Ammonitidte.  The  remains  by  which 
these  animals  are  recognized  are  necessarily  less  perfect,  as  a 
rule,  than  those  of  the  latter,  as  no  external  shell  is  present 
(except  in  rare  and  more  modern  groups),  and  the  internal 
skeleton  is  not  necessarily  calcareous.  Nevertheless,  we  have 
an  ample  record  of  the  Cuttle-fishes  of  the  Jurassic  period,  in 
the  shape  of  the  fossilized  jaws  or  beak,  the  ink-bag,  and,  most 
commonly  of  all,  the  horny  or  calcareous  structure  which  is 
embedded  in  the  soft  tissues,  and  is  variously  known  as  the 
"  pen "  or  "  bone. "  The  beaks  of  Cuttle-fishes,  though  not 
abundant,  are  sufficiently  plentiful  to  have  earned  for  them- 
selves the  general  title  of  "  Rhyncholites ; "  and  in  their  form 
and  function  they  resemble  the  horny,  parrot-like  beak  of  the 
existing  Cephalopods.  The  ink-bag  or  leathery  sac  in  which 
the  Cuttle-fishes  store  up  the  black  pigment  with  which  they 
obscure  the  water  when  attacked,  owes  its  preservation  to  the 
fact  that  the  coloring-matter  which  it  contains  is  finely-divided 
carbon,  and  therefore  nearly  indestructible  except  by  heat. 
Many  of  these  ink-bags  have  been  found  in  the  Lias;  and  the 


THE  JURASSIC  PERIOD. 


247 


coloring-matter  is  sometimes  so  well  preserved  that  it  has 
been,  as  an  experiment,  employed  in  painting  as  a  fossil 
"  sepia. "  The  "  pens  "  of  the  Cuttle-fishes  are  not  commonly 
preserved,  owing  to  their  horny  consistence,  but  they  are  not 
unknown.  The  form  here  figured  (Beloteuthis  subcostata,  fig. 
172)  belonged  to  an  old  type  essentially  similar  to  our  modern 
Calamaries,  the  skeleton  of  which  consists  of  a  horny  shaft 
and  two  lateral  wings,  somewhat  like  a  feather  in  general 
shape.  When,  on  the  other  hand,  the  internal  skeleton  is 
calcareous,  then  it  is  very  easily  preserved 
in  a  fossil  condition;  and  the  abundance 
of  remains  of  this  nature  in  the  Secondary 
rocks,  combined  with  their  apparent  total 
absence  in  Palaeozoic  strata,  is  a  strong  pre- 
sumption in  favor  of  the  view  that  the  order 
of  the  Cuttle-fishes  did  not  come  into  exist- 
ence till  the  commencement  of  the  Meso- 
zoic  period.  The  great  majority  of  the  skele- 
tons of  this  kind  which  are  found  in  the  Jur- 
assic rocks  belong  to  the  great  extinct  family 
of  the  "Belemnites"  (Belemnitidce},  which,  so 
far  as  known,  is  entirely  confined  to  rocks 
of  Secondary  age.  From  its  pointed, '  gener- 
ally cylindro-conical  form,  the  skeleton  of 
the  Belemnite  is  popularly  Known  as  a  "thun- 
derbolt" (fig.  173,  C).  In  its  perfect  condition 
— in  which  it  is,  however,  rarely  obtainable — 
the  skeleton  consists  of  a  chambered  conical 
shell  (the  "  phragmacone  "),  the  partitions  between  the  chambers 
of  which  are  pierced  by  a  marginal  tube  or  "  Siphuncle. "  This 
conical  shell — curiously  similar  in  its  structure  to  the  external 
shell  of  the  Nautilus — is  extended  forwards  into  a  horny 
"pen,"  and  is  sunk  in  a  corresponding  conical  pit  (fig.  173,  B), 
excavated  in  the  substance  of  a  nearly  cylindrical  fibrous 
body  or  "guard,"  which  projects  backwards  for  a  longer  or 
shorter  distance,  and  is  the  part  most  usually  found  in  a  fossil 
condition.  Many  different  kinds  of  Belemnites  are  known,  and 
their  guards  literally  swarm  in  many  parts  of  the  Jurassic  series, 
whilst  some  specimens  attain  very  considerable  dimensions. 
Not  only  is  the  internal  skeleton  known,  but  specimens  of 
Belemnites  and  the  nearly  allied  Belemnoteuthis  have  been  found 
in  some  of  the  fine-grained  sediments  of  the  Jurassic  formation, 
from  which  much  has  been  learnt  even  as  to  the  anatomy  of 


Fig.  172.—  Beioteu- 
Jur" 


248 


HISTORICAL  PALAEONTOLOGY. 


the  soft  parts  of  the  animal.     Thus  we  know  that  the  Belem- 
nites    were    in    many    respects    comparable    with    the    existing 


Fig.  173.— A,  Restoration  of  the  animal  of  the  Belemnite  ;  B,  Diagram  showing  the 
complete  skeleton  of  a  Belemnite,  consisting  of  the  chambered  phragmacone  (a;,  the 
guard  (6),  and  the  horny  pen  (c) ;  C,  Specimen  of  Belemnites  canaliculatus,  from  the 
Inferior  Oolite.  (After  Phillips.) 


Calamaries    or    Squids,    the    body    being    furnished    with    lateral 
fins,   and   the   head   carrying   a   circle   of   ten    "  arms, "   two   of 


Fig.  Yl^.—Tetragonolepis  (restored),  and  scales  of  the  same.    Lias. 

which  were  longer  than  the  others   (fig.   173,  A).     The  suckers 
on  the  arms  were  provided,   further,  with  horny  hooks;   there 


THE  JURASSIC  PERIOD. 


249 


was   a   large   ink-sac ;    and   the   mouth   was   armed   with   horny 
mandibles  resembling  in  shape  the  beak  of  a  parrot. 

Coming  next  to  the  Vertebrates,  we  find  that  the  Jurassic 
Fishes  are  still  represented  by  Ganoids  and  Placoids.  The 
Ganoids,  however,  unlike  the  old  forms,  now  for  the  most 
part  possess  nearly  or  quite  symmetrical  ("  homocercal")  tails. 
A  characteristic  genus  is  Tetragonolepis  (fig.  174),  with  its 
deep,  compressed  body,  its  rhomboidal,  closely-fitting  scales, 
and  its  single  long  dorsal  fin.  Amongst  the  Placoids  the  teeth 
of  true  Sharks  (Notidanus)  occur  for  the  first  time;  but  by  far 
the  greater  number  of  remains  referable  to  this  group  are  still 
the  fin-spines  and  teeth  of  "  Cestracionts, "  resembling  the 
living  Port-Jackson  Shark.  Some  of  these  teeth  are  pointed 
(Hybodus}  ;  but  others  are  rounded,  and  are  adapted  for  crush- 
ing shell-fish.  Of  these  latter,  the  commonest  are  the  teeth  of 
Acrodus  (fig.  175),  of  which  the  hinder  ones  are  of  an  elon- 
gated form,  with  a  rounded 
surface,  covered  with  fine 
transverse  striae  proceed- 
ing from  a  central  longi- 
tudinal line.  From  their 
general  form  and  striation, 
and  their  dark  color,  these 
teeth  are  commonly  called 
"  fossil  leeches  "  by  the  quarrymen. 

The  Amphibian  group  of  the  Labyrinthodonts,  which  was  so 
extensively  developed  in  the  Trias,  appears  to  have  become 
extinct,  no  representative  of  the  order  having  hitherto  been 
detected  in  rocks  of  Jurassic  age. 

Much  more  important  than  the  Fishes  of  the  Jurassic  series 
are  the  Reptiles,  which  are  both  very  numerous,  and  belong  to 
a  great  variety  of  types,  some  of  these  being  very  extraordinary 


Fig.  175.— Tooth  of  Acrodut  nobilis.    Lias. 


Fig.  176. — Ichthyosaurus  communis.     Lias. 

in  their  anatomical  structure.  The  predominant  group  is  that 
of  the  "  Enaliosaurs  "  or  "  Sea-lizards, "  divided  into  two  great 
orders,  represented  respectively  by  the  Ichthyosaurus  and  the 
Plesiosaurus. 


250  HISTORICAL  PALEONTOLOGY. 

The  Ichthyosauri  or  "Fish-Lizards"  are  exclusively  Meso- 
zoic  in  their  distribution,  ranging  from  the  Lias  to  the  Chalk, 
but  abounding  especially  in  the  former.  They  were  huge 
Reptiles,  of  a  fish-like  form,  with  a  hardly  conspicuous  neck 
(fig.  176),  and  probably  possessing  a  simply  smooth  or 
wrinkled  skin,  since  no  traces  of  scales  or  bony  integumentary 
plates  have  ever  been  discovered.  The  tail  was  long,  and 
was  probably  furnished  at  its  extremity  with  a  powerful  ex- 
pansion of  the  skin,  constituting  a  tail-fin  similar  to  that  pos- 
sessed by  the  Whales.  The  limbs  are  also  like  those  of  Whales 
in  the  essentials  of  their  structure,  and  in  their  being  adapted 
to  act  as  swimming-paddles.  Unlike  the  Whales,  however, 
the  Ichthyosaurs  possessed  the  hind-limbs  as  well  as  the  fore- 
limbs,  both  pairs  having  the  bones  flattened  out  and  the  fin- 
gers completely  enclosed  in  the  skin,  the  arm  and  leg  being  at 
the  same  time  greatly  shortened.  The  limbs  are  thus  con- 
verted into  efficient  "flippers,"  adapting  the  animal  for  an 
active  existence  in  the  sea.  The  different  joints  of  the  back- 
bone (vertebrae)  also  show  the  same  adaptation  to  an  aquatic 
mode  of  life,  being  hollowed  out  at  both  ends,  like  the  bicon- 
cave vertebrae  of  Fishes.  The  spinal  column  in  this  way  was 
endowed  with  the  flexibility  necessary  for  an  animal  intended 
to  pass  the  greater  part  of  its  time  in  water.  Though  the  Ich- 
thyosaurs are  undoubtedly  marine  animals,  there  is,  however, 
reason  to  believe  that  they  occasionally  came  on  shore,  as  they 
possess  a  strong  bony  arch,  supporting  the  fore-limbs,  such  as 
would  permit  of  partial,  if  laborious,  terrestrial  progression. 
The  head  is  of  enormous  size,  with  greatly  prolonged  jaws, 
holding  numerous  powerful  conical  teeth  lodged  in  a  common 
groove.  The  nature  of  the  dental  apparatus  is  such  as  to 
leave  no  doubt  as  to  the  rapacious  and  predatory  habits  of  the 
Ichthyosaurs — an  inference  which  is  further  borne  out  by  the 
examination  of  their  petrified  droppings,  which  are  known  to 
geologists  as  "  coprolites, "  and  which  contain  numerous  frag- 
ments of  the  bones  and  scales  of  the  Ganoid  fishes  which 
inhabited  the  same  seas.  The  orbits  are  of  huge  size ;  and  as 
the  eyeball  was  protected,  like  that  of  birds,  by  a  ring  of  bony 
plates  in  its  outer  coat,  we  even  know  that  the  pupils  of  the 
eyes  were  of  correspondingly  large  dimensions.  As  these  bony 
plates  have  the  function  of  protecting  the  eye  from  injury 
under  sudden  changes  of  pressure  in  the  surrounding  medium, 
it  has  been  inferred,  with  great  probability,  that  the  Ichthy- 
osaurs were  in  the  habit  of  diving  to  considerable  depths  in 


THE  JURASSIC  PERIOD. 


251 


the  sea.  Some  of  the  larger  specimens  of  Ichthyosaurus  which 
have  been  discovered  in  the  Lias  indicate  an  animal  of  from 
20  to  nearly  40  feet  in  length;  and  many  species  are  known  to 
have  existed,  whilst  fragmentary  remains  of  their  skeletons  are 
very  abundant  in  some  localities.  We  may  therefore  safely 
conclude  that  these  colossal  Reptiles  were  amongst  the  most 
formidable  of  the  many  tyrants  of  the  Jurassic  seas. 

The  Plesiosaurus  (fig.  177)  is  another  famous  Oolitic 
Reptile,  and,  like  the  preceding,  must  have  lived  mainly  or 
exclusively  in  the  sea.  It  agrees  with  the  Ichthyosaur  in  some 
important  features  of  its  organization,  especially  in  the  fact 
that  both  pairs  of  limbs  are  converted  into  "  flippers "  or 
swimming-paddles,  whilst  the  skin  seems  to  have  been  equally 
destitute  of  any  scaly  or  bony  investiture.  Unlike  the  Ichthy- 


Fig.  in.—Plesiosauru8  dolicfiodeirua , restored.    Lias. 

osaur,  however,  the  Plesiosaur  had  the  paddles  placed  far  back, 
the  tail  being  extremely  short,  and  the  neck  greatly  lengthened 
out,  and  composed  of  from  twenty  to  forty  vertebrae.  The 
bodies  of  the  vertebras,  also,  are  not  deeply  biconcave,  but  are 
flat,  or  only  slightly  cupped.  The  head  is  of  relatively  small 
size,  with  smaller  orbits  than  those  of  the  Ichthyosaur,  and  with 
a  snout  less  elongated.  The  jaws,  however,  were  armed  with 
numerous  conical  teeth,  inserted  in  distinct  sockets.  As  re- 
gards the  habits  of  the  Plesiosaur,  Dr.  Conybeare  arrives  at  the 
following  conclusions:  "That  it  was  aquatic  is  evident  from 
the  form  of  its  paddles;  that  it  was  marine  is  almost  equally 
so  from  the  remains  with  which  it  is  universally  associated; 


252  HISTORICAL  PALEONTOLOGY. 

that  it  may  have  occasionally  visited  the  shore,  the  resem- 
blance of  its  extremities  to  those  of  the  Turtles  may  lead  us  to 
conjecture:  its  movements,  however,  must  have  been  very 
awkward  on  land;  and  its  long  neck  must  have  impeded  its 
progress  through  the  water,  presenting  a  strong  contrast  to  the 
organization  which  so  admirably  fits  the  Ichthyosaurus  to  cut 
through  the  waves. "  As  its  respiratory  organs  were  such  that 
it  must  of  necessity  have  required  to  obtain  air  frequently,  we 
may  conclude  "that  it  swam  upon  or  near  the  surface,  arching 
back  its  long  neck  like  a  swan,  and  occasionally  darting  it 
down  at  l!ie  fish  which  happened  to  float  within  its  reach.  It 
may  perhaps  have  lurked  in  shoal  water  along  the  coast,  con- 
cealed amongst  the  sea-weed ;  and  raising  its  nostrils  to  a 
level  with  the  surface  from  a  considerable  depth,  may  have 
found  a  secure  retreat  from  the  assaults  of  powerful  enemies; 
while  the  length  and  flexibility  of  its  neck  may  have  compen- 
sated for  the  want  of  strength  in  its  jaws,  and  its  incapacity 
for  swift  motion  through  the  water. " 

About  twenty  species  of  Plesiosaurus  are  known,  ranging 
from  the  Lias  to  the  Chalk,  and  specimens  have  been  found 
indicating  a  length  of  from  eighteen  to  twenty  feet.  The 
nearly  related  "  Pliosaurs,"  however,  with  their  huge  heads 
and  short  necks,  must  have  occasionally  reached  a  length  of  at 
least  forty  feet — the  skull  in  some  species  being  eight,  and  the 
paddles  six  or  seven  feet  long,  whilst  the  teeth  are  a  foot  in 
length. 

Another  extraordinary  group  of  Jurassic  Reptiles  is  that  of 
the  "  Winged  Lizards  "  or  Pterosauria.  These  are  often  spoken 
of  collectively  as  "  Pterodactyles, "  from  Pterodactylus,  the 
type-genus  of  the  group.  As  now  restricted,  however,  the 
genus  Pterodactylus  is  more  Cretaceous  than  Jurassic,  and  it  is 
associated  in  the  Oolitic  rocks  with  the  closely  allied  genera 
Dimorphodon  and  Rhamphorhynchus.  In  all  three  of  these 
genera  we  have  the  same  general  structural  organization,  in- 
volving a  marvellous  combination  of  characters,  which  we  are  in 
the  habit  of  regarding  as  peculiar  to  Birds  on  the  one  hand,  to 
Reptiles  on  another  hand,  and  to  the  Flying  Mammals  or 
Bats  in  a  third  direction.  The  "  Pterosaurs "  are  "  Flying " 
Reptiles,  in  the  true  sense  of  the  term,  since  they  were  indu- 
bitably possessed  of  the  power  of  active  locomotion  in  the  air, 
after  the  manner  of  Birds.  The  so-called  "Flying"  Reptiles 
of  the  present  day,  such  as  the  little  Draco  volans  of  the  East 
Indies  and  Indian  Archipelago,  possess,  on  the  other  hand,  no 


THE  JURASSIC  PERIOD.  253 

power  of  genuine  flight,  being  merely  able  to  sustain  themselves 
in  the  air  through  the  extensive  leaps  which  they  take  from  tree 
to  tree,  the  wing-like  expansions  of  the  skin  simply  exercising 
the  mechanical  function  of  a  parachute.  The  apparatus  of  flight 
in  the  "  Pterosaurs "  is  of  the  most  remarkable  character,  and 
most  resembles  the  "  wing "  of  a  Bat,  though  very  different  in 
some  important  particulars.  The  "  wing "  of  the  Pterosaurs  is 
like  that  of  Bats,  namely,  in  consisting  of  a  thin  leathery  expan- 
sion of  the  skin  which  is  attached  to  the  sides  of  the  body,  and 
stretches  between  the  fore  and  hind  limbs,  being  mainly  sup- 
ported by  an  enormous  elongation  of  certain  of  the  digits  of 


Fig.  I1%.—Pterodactylu8  crasslrostris.  From  the  Lithographic  Slates  of  Solenhofen 
(Middle  Oolite. )  The  figure  is  "  restored,"  and  it  seems  certain  that  the  restoration 
is  incorrect  in  the  comparatively  unimportant  particular,  that  the  hand  should  consist 
of  no  more  than  four  fingers,  three  short  and  one  long,  Instead  of  five,  as  represented. 

the  hand.  In  the  Bats,  it  is  the  four  outer  fingers  which  are 
thus  lengthened  out;  but  in  the  Pterosaurs,  the  wing-membrane 
is  borne  by  a  single  immensely-extended  finger  (fig.  178). 
No  trace  of  the  actual  wing-membrane  itself  has,  of  course, 
been  found  fossilized ;  but  we  could  determine  that  the  "  Ptero- 
dactyles  "  possessed  the  power  of  flight,  quite  apart  from  the  ex- 
traordinary conformation  of  the  hand.  The  proofs  of  this  are  to 
be  found  partly  in  the  fact  that  the  breast-bone  was  furnished 
with  an  elevated  ridge  or  keel,  serving  for  the  attachment  of 
the  great  muscles  of  flight,  and  still  more  in  the  fact  that  the 


254  HISTORICAL  PALEONTOLOGY. 

bones  were  hollow  and  were  filled  with  air — a  peculiarity 
wholly  confined  amongst  living  animals  to  Birds  only.  The 
skull  of  the  Pterosaurs  is  long,  light,  and  singularly  bird-like  in 
appearance — a  resemblance  which  is  further  increased  by  the 
comparative  length  of  the  neck  and  the  size  of  the  vertebrae  of 
this  region  (fig.  178).  The  jaws,  however,  unlike  those  of  any 
existing  Bird,  were,  with  one  exception  to  be  noticed  hereafter, 
furnished  with  conical  teeth  sunk  in  distinct  sockets;  and 
there  was  always  a  longer  or  shorter  tail  composed  of  distinct 
vertebrae ;  whereas  in  all  existing  Birds  the  tail  is  abbreviated, 
and  the  terminal  vertebrae  are  amalgamated  to  form  a  single 
bone,  which  generally  supports  the  great  feathers  of  the  tail. 

Modern  naturalists  have  been  pretty  generally  agreed  that 
the  Pterosaurs  should  be  regarded  as  a  peculiar  group  of  the 
Reptiles;  though  they  have  been  and  are  still  regarded  by 
high  authorities,  like  Professor  Seeley,  as  being  really  referable 
to  the  Birds,  or  as  forming  a  class  by  themselves.  The  chief 
points  which  separate  them  from  Birds,  as  a  class,  are  the 
character  of  the  apparatus  of  flight,  the  entirely  different  struc- 
ture of  the  fore-limb,  the  absence  of  feathers,  the  composition 
of  the  tail  out  of  distinct  vertebrae,  and  the  general  presence 
of  conical  teeth  sunk  in  distinct  sockets  in  the  jaws.  The  gap 
between  the  Pterosaurs  and  the  Birds  has,  however,  been 
greatly  lessened  of  late  by  the  discovery  of  fossil  animals 
(Ichthyornis  and  Hesperornis}  with  the  skeleton  proper  to  Birds 
combined  with  the  presence  of  teeth  in  the  jaws,  and  by  the 
still  more  recent  discovery  of  other  fossil  animals  (Pteranodon) 
with  a  Pterosaurian  skeleton,  but  without  teeth;  whilst  the  un- 
doubtedly feathered  Archaopteryx  possessed  a  long  tail  com- 
posed of  separate  vertebras.  Upon  the  whole,  therefore,  the 
relationships  of  the  Pterosaurs  cannot  be  regarded  as  absolutely 
settled.  It  seems  certain,  however,  that  they  did  not  possess 
feathers — this  implying  that  they  were  cold-blooded  animals; 
and  their  affinities  with  Reptiles  in  this,  as  in  other  characters, 
are  too  strong  to  be  overlooked. 

The  Pterosaurs  are  wholly  Mesozoic,  ranging  from  the  Lias 
to  the  Chalk  inclusive;  and  the  fine-grained  Lithographic  Slate 
of  Solenhofen  has  proved  to  be  singularly  rich  in  their  remains. 
The  genus  Pterodactylus  itself  has  the  jaws  toothed  to  the  ex- 
tremities with  equal-sized  conical  teeth,  and  its  species  range 
from  the  Middle  Oolites  to  the  Cretaceous  series,  in  connec- 
tion with  which  they  will  be  again  noticed,  together  with  the 
toothless  genus  Pteranodon.  The  genus  Dimorphodon  is  Li- 


THE  JURASSIC  PERIOD.  255 

assic,  and  is  characterized  by  having  the  front  teeth  long  and 
pointed,  whilst  the  hinder  teeth  are  small  and  lancet-shaped. 
Lastly,  the  singular  genus  Rhamphorhynchus,  also  from  the 
Lower  Oolites,  is  distinguished  by  the  fact  that  there  are  teeth 
present  in  the  hinder  portions  of  both  jaws;  but  the  front  por- 
tions are  toothless,  and  may  have  constituted  a  horny  beak. 
Like  most  of  the  other  Jurassic  Pterosaurs,  Rhamphorhynchus 
(fig.  179)  does  not  seem  to  have  been  much  bigger  than  a 
pigeon,  in  this  respect  falling  far  below  the  giant  "  Dragons " 
of  the  Cretaceous  period.  It  differed  from  its  relatives,  not 


Fig.  IVZ.—Rhamphorhynchua  Bucklandi,  restored.     Bath  Oolite,  England. 
(After  the  late  Professor  Phillips.) 

only  in  the  armature  of  the  mouth,  but  also  in  the  fact  that 
the  tail  was  of  considerable  length.  With  regard  to  its  habits 
and  mode  of  life,  Professor  Phillips  remarks  that,  "gifted  with 
ample  means  of  flight,  able  at  least  to  perch  on  rocks  and 
scuffle  along  the  shore,  perhaps  competent  to  dive,  though  not 
so  well  as  a  Palmiped  bird,  many  fishes  must  have  yielded  to 
the  cruel  beak  and  sharp  teeth  of  Rhamphorhynchus.  If  we 
ask  to  which  of  the  many  families  of  Birds  the  analogy  of 
structure  and  probable  way  of  life  would  lead  us  to  assimilate 
Rhamphorhynchus,  the  answer  must  point  to  the  swimming 
races  with  long  wings,  clawed  feet,  hooked  beak,  and  habits  of 
violence  and  voracity;  and  for  preference,  the  shortness  of  the 
legs,  and  other  circumstances,  may  be  held  to  claim  for  the 
Stonesfield  fossil  a  more  than  fanciful  similitude  to  the  groups 
of  Cormorants,  and  other  marine  divers,  which  constitute  an 
effective  part  of  the  picturesque  army  of  robbers  of  the  sea. " 

Another  extraordinary  and  interesting  group  of  the  Meso- 
zoic  Reptiles  is  constituted  by  the  Deinosauria,  comprising  a 
series  of  mostly  gigantic  forms,  which  range  from  the  Trias  to 
the  Chalk.  All  the  "  Deinosaurs  "  are  possessed  of  the  two  pairs 
of  limbs  proper  to  Vertebrate  animals,  and  these  organs  are  in 
the  main  adapted  for  walking  on  the  dry  land.  Thus,  whilst 


256 


HISTORICAL  PALEONTOLOGY. 


the  Mesozoic  seas  swarmed  with  the  huge  Ichthyosaurs  and 
Plesiosaurs,  and  whilst  the  air  was  tenanted  by  the  Dragon-like 
Pterosaurs,  the  land-surfaces  of  the  Secondary  period  were 
peopled  by  numerous  forms  of  Deinosaurs,  some  of  them  of 
even  more  gigantic  dimensions  than  their  marine  brethren. 
The  limbs  of  the  Deinosaurs  are,  as  just  said,  adapted  for  pro- 
gression on  the  land;  but  in  some  cases,  at  any  rate,  the 
hind-limbs  were  much  longer  and  stronger  than  the  fore-limbs; 
and  there  seems  to  be  no  reason  to  doubt  that  many  of  these 
forms  possessed  the  power  of  walking,  temporarily  or  perman- 
ently, on  their  hind-legs,  thus  presenting  a  singular  resemblance 
to  Birds.  Some  very  curious  and  striking  points  connected 
with  the  structure  of  the  skeleton  have  also  been  shown  to 
connect  these  strange  Reptiles  with  the  true  Birds ;  and  such 
high  authorities  as  Professors  Huxley  and  Cope  are  of  opinion 
that  the  Deinosaurs  are  distinctly  related  to  this  class,  being  in 
some  respects  intermediate  between  the  proper  Reptiles  and 
the  great  wingless  Birds,  like  the  Ostrich  and  Cassowary.  On 
the  other  hand,  Professor  Owen  has  shown  that  the  Deinosaurs 
possess  some  weighty  points  of  relationship  with  the  so-called 


Fig.  180.— Skull  of  Megalosaurus,  on  a  scale  one-tenth  of  nature.    Restored. 
(After  Professor  Phillips.) 

"  Pachydermatous "  Quadrupeds,  such  as  the  Rhinoceros  and 
Hippopotamus.  The  most  important  Jurassic  genera  of 
Deinosauria  are  Megalosaurus  and  Cetiosaurus,  both  of  which 
extend  their  range  into  the  Cretaceous  period,  in  which 
flourished,  as  we  shall  see,  some  other  well-known  members 
of  this  order. 


THE  JURASSIC  PERIOD.  257 

Megalosaurus  attained  gigantic  dimensions,  its  thigh  and 
shank  bones  measuring  each  about  three  feet  in  length,  and  its 
total  length,  including  the  tail,  being  estimated  at  from  forty 
to  fifty  feet.  As  the  head  of  the  thigh-bone  is  set  on  nearly 
at  right  angles  with  the  shaft,  whilst  all  the  long  bones  of  the 
skeleton  are  hollowed  out  internally  for  the  reception  of  the 
marrow,  there  can  be  no  doubt  as  to  the  terrestrial  habits  of 
the  animal.  The  skull  (fig.  180)  was  of  large  size,  four  or  five 
feet  in  length,  and  the  jaws  were  armed  with  a  series  of  power- 
ful pointed  teeth.  The  teeth  are  conical  in  shape,  but  are 
strongly  compressed  towards  their  summits,  their  lateral  edges 
being  finely  serrated.  In  their  form  and  their  saw-like  edges, 
they  resemble  the  teeth  of  the  "  Sabre-toothed  Tiger "  Machai- 
rodus},  and  they  render  it  certain  that  the  Megalosaur  was  in 
the  highest  degree  destructive  and  carnivorous  in  its  habits. 
So  far  as  is  known,  the  skin  was  not  furnished  with  any  armor 
of  scales  or  bony  plates ;  and  the  fore-limbs  are  so  dispro- 
portionately small  as  compared  with  the  hind-limbs,  that  this 
huge  Reptile — like  the  equally  huge  Iguanodon — may  be 
conjectured  to  have  commonly  supported  itself  on  its  hind- 
legs  only. 

The  Cetiosaur  attained  dimensions  even  greater  than  those 
of  the  Megalosaur,  one  of  the  largest  thigh-bones  measuring 
over  five  feet  in  length  and  a  foot  in  diameter  in  the  middle, 
and  the  total  length  of  the  animal  being  probably  not  less  than 
fifty  feet.  It  was  originally  regarded  as  a  gigantic  Crocodile, 
but  it  has  been  shown  to  be  a  true  Deinosaur.  Having  ob- 
tained a  magnificent  series  of  remains  of  this  reptile,  Professor 
Phillips  has  been  able  to  determine  many  very  interesting 
points  as  to  the  anatomy  and  habits  of  this  colossal  animal, 
the  total  length  of  which  he  estimates  as  being  probably  not 
less  than  sixty  or  seventy  feet.  As  to  its  mode  of  life,  this 
accomplished  writer  remarks  : — 

"  Probably  when  '  standing  at  ease '  not  less  than  ten  feet 
in  height,  and  of  a  bulk  in  proportion,  this  creature  was  un- 
matched in  magnitude  and  physical  strength  by  any  of  the 
largest  inhabitants  of  the  Mesozoic  land  or  sea.  Did  it  live 
in  the  sea,  in  fresh  waters,  or  on  the  land?  This  question 
cannot  be  answered,  as  in  the  case  of  Ichthyosaurus,  by  appeal 
to  the  accompanying  organic  remains ;  for  some  of  the  bones 
lie  in  marine  deposits,  others  in  situations  marked  by  estuarine 
conditions,  and,  out  of  the  Oxfordshire  district,  in  Sussex,  in 
fluviatile  accumulations.  Was  it  fitted  to  live  exclusively  in 
17 


258  HISTORICAL  PALEONTOLOGY. 

water?  Such  an  idea  was  at  one  time  entertained,  in  conse- 
quence of  the  biconcave  character  of  the  caudal  vertebrae,  and 
it  is  often  suggested  by  the  mere  magnitude  of  the  creature, 
which  would  seem  to  have  an  easier  life  while  floating  in  water, 
than  when  painfully  lifting  its  huge  bulk,  and  moving  with 
slow  steps  along  the  ground.  But  neither  of  these  arguments 
is  valid.  The  ancient  earth  was  trodden  by  larger  quadrupeds 
than  our  elephant;  and  the  biconcave  character  of  vertebrae, 
which  is  not  uniform  along  the  column  in  Cetiosaurus,  is  per- 
haps as  much  a  character  of  geological  period  as  of  a  me- 
chanical function  of  life.  Good  evidence  of  continual  life  in 
water  is  yielded  in  the  case  of  Ichthyosaurus  and  other  Ena- 
liosaurs,  by  the  articulating  surfaces  of  their  limb-bones,  for 
these,  all  of  them,  to  the  last  phalanx,  have  that  slight  and 
indefinite  adjustment  of  the  bones,  with  much  intervening 
cartilage,  which  fits  the  leg  to  be  both  a  flexible  and  forcible 
instrument  of  natation,  much  superior  to  the  ordinary  oar- 
blade  of  the  boatman.  On  the  contrary,  in  Cetiosaur,  as  well 
as  in  Megalosaur  and  Iguanodon,  all  the  articulations  are 
definite,  and  made  so  as  to  correspond  to  determinate  move- 
ments in  particular  directions,  and  these  are  such  as  to  be 
suited  for  walking.  In  particular,  the  femur,  by  its  head  pro- 
jecting freely  from  the  acetabulum,  seems  to  claim  a  movement 
of  free  stepping  more  parallel  to  the  line  of  the  body,  and 
more  approaching  to  the  vertical  than  the  sprawling  gait  of 
the  crocodile.  The  large  claws  concur  in  this  indication  of 
terrestrial  habits.  But,  on  the  other  hand,  these  characters 
are  not  contrary  to  the  belief  that  the  animal  may  have  been 
amphibious ;  and  the  great  vertical  height  of  the  anterior  part 
of  the  tail  seems  to  support  this  explanation,  but  it  does  not 
go  further.  .  .  .  We  have  therefore  a  marsh-loving  or 
river-side  animal,  dwelling  amidst  filicine,  cycadaceous,  and 
coniferous  shrubs  and  trees  full  of  insects  and  small  mamma- 
lia. What  was  its  usual  diet?  If  ex  ungue  leonem,  surely  ex 
dente  cibum.  We  have  indeed  but  one  tooth,  and  that  small 
and  incomplete.  It  resembles  more  the  tooth  of  Iguanodon 
than  that  of  any  other  reptile;  for  this  reason  it  seems  prob- 
able that  the  animal  was  nourished  by  similar  vegetable  food 
which  abounded  in  the  vicinity,  and  was  not  obliged  to  con- 
tend with  Megalosaurus  for  a  scanty  supply  of  more  stimu- 
lating diet. " 

All  the  groups  of  Jurassic  Reptiles  which  we  have  hitherto 
been  considering  are  wholly  unrepresented  at  the  present  day, 


THE  JURASSIC  PERIOD. 


259 


3.nd  do  not  even  pass  upwards  into  the  Tertiary  period.  It 
may  be  mentioned,  however,  that  the  Oolitic  deposits  have 
also  yielded  the  remains  of  Reptiles  belonging  to  three  of  the 
existing  orders  of  the  class — namely,  the  Lizards  (Lacertilia), 


Fig.  181. — Arc/tcKopteryx  macrura,  showing  tall  and  tail-feathers,  with  detached  bones. 
Reduced.    From  the  Lithographic  Slate  of  Solenhofen. 

the  Turtles  (Chelonia},  and  the  Crocodiles  (Crocodilia).  The 
Lizards  occur  both  in  the  marine  strata  of  the  Middle  Oolites 
and  also  in  the  fresh-water  beds  of  the  Purbeck  series;  and 


Fig.  182.— Restoration  of  Arckceopteryx  macrura.    (After  Owen). 

they  are  of  such  a  nature  that  their  affinities  with  the  typical 
Lacertilians  of  the  present  day  cannot  be  disputed.  The 
Chelonians,  up  to  this  point  only  known  by  the  doubtful  evi- 


260  HISTORICAL  PALEONTOLOGY. 

dence  of  footprints  in  the  Permian  and  Triassic  sandstones,  are 
here  represented  by  unquestionable  remains,  indicating  the  ex- 
istence of  marine  Turtles  (the  Chelone  planiceps  of  the  Portland 
Stone).  No  remains  of  Serpents  (Ophidians}  have  as  yet  been 
detected  in  the  Jurassic;  but  strata  of  this  age  have  yielded 
the  remains  of  numerous  Crocodilians,  which  probably  inhab- 
ited the  sea.  The  most  important  member  of  this  group  is 
Teleosaurus,  which  attained  a  length  of  over  thirty  feet,  and 
is  in  some  respects  allied  to  the  living  Gavials  of  India. 

The  great  class  of  the  Birds,  as  we  have  seen,  is  represented 
in  rocks  earlier  than  the  Oolites  simply  by  the  not  absolutely 
certain  evidence  of  the  three-toed  footprints  of  the  Connecti- 
cut Trias.  In  the  Lithographic  Slate  of  Solenhofen  (Middle 
Oolite),  there  has  been  discovered,  however,  the  at  present 
unique  skeleton  of  a  Bird  well  known  under  the  name  of  the 
Archaopteryx  macrura  (figs.  181,  182).  The  only  known 
specimen — now  in  the  British  Museum — unfortunately  does 
not  exhibit  the  skull ;  but  the  fine-grained  matrix  has  pre- 
served a  number  of  the  other  bones  of  the  skeleton,  along  with 
the  impressions  of  the  tail  and  wing  feathers.  From  these 
remains  we  know  that  Archaopteryx  differed  in  some  remark- 
able peculiarities  of  its  structure  from  all  existing  members  of 
the  class  of  Birds.  This  extraordinary  Bird  (fig.  182)  appears 
to  have  been  about  as  big  as  a  Rook — the  tail  being  long  and 
extremely  slender,  and  composed  of  separate  vertebrae,  each 
of  which  supports  a  single  pair  of  quill-feathers.  In  the  flying 
Birds  of  the  present  day,  as  before  mentioned,  the  terminal 
vertebrae  of  the  tail  are  amalgamated  to  form  a  single  bone 
("ploughshare-bone"),  which  supports  a  cluster  of  tail-feathers; 
and  the  tail  itself  is  short.  In  the  embryos  of  existing  Birds 
the  tail  is  long,  and  is  made  up  of  separate  vertebrae,  and  the 
same  character  is  observed  in  many  existing  Reptiles.  The 
tail  of  Archoeopteryx,  therefore,  is  to  be  regarded  as  the  per- 
manent retention  of  an  embryonic  type  of  structure,  or  as  an 
approximation  to  the  characters  of  the  Reptiles.  Another 
remarkable  point  in  connection  with  Archaopteryx,  in  which 
it  differs  from  all  known  Birds  is,  that  the  wing  was  furnished 
with  two  free  claws.  From  the  presence  of  feathers,  Archce- 
opteryx  may  be  inferred  to  have  been  hot-blooded;  and  this 
character,  taken  along  with  the  structure  of  the  skeleton  of  the 
wing,  may  be  held  as  sufficient  to  justify  its  being  considered 
as  belonging  to  a  class  of  Birds.  In  the  structure  of  the 
tail,  however,  it  is  singularly  Reptilian;  and  there  is  reason  to 


THE  JURASSIC  PERIOD. 


261 


believe  that  its  jaws  were  furnished  with  teeth  sunk  in  distinct 
sockets,  as  is  the  case  in  no  existing  Bird.  This  conclusion, 
at  any  rate,  is  rendered  highly  probable  by  the  recent  discovery 
of  "Toothed  Birds"  (Odontornithes)  in  the  Cretaceous  rocks 
of  North  America. 

The  Mammals  of  the  Jurassic  period  are  known  to  us  by 
a  number  of  small  forms  which  occur  in  the  "  Stonesfield 
Slate"  (Great  Oolite)  and  in  the  Purbeck  beds  (Upper 
Oolite).  The  remains  of  these  are  almost  exclusively  sepa- 
rated halves  of  the  lower  jaw,  and  they  indicate  the  existence 


Fig.  183. — Lower  jaw  of  Ampkitherium  ( Thylacotherium)  PrevosM, 
Stonesfield  Slate  (Great  Oolite.) 

during  the  Oolitic  period  in  Europe  of  a  number  of  small 
"Pouched  animals"  (Marsupials).  In  the  horizon  of  the 
Stonesfield  Slate  four  genera  of  these  little  Quadrupeds  have 
been  described — viz.,  Amphilestes,  Amphitherium,  Phascolo- 
therium,  and  Stereognathus.  In  Amphitherium  (fig.  183),  the 
molar  teeth  are  'furnished  with  small  pointed  eminences  of 
"  cusps ; "  and  the  animal  was  doubtless  insectivorous.  By 


Fig.  184  —Oolitic  Mammals.— 1,  Lower  jaw  and  teeth  of  Pkaacolotherium,  Stones- 
field  Slate  ;  2.  Lower  jaw  and  teeth  of  Amphitherium,  Stonesfield  Slate  ;  3,  Lower  jaw 
and  teeth  of  Triconodon.  Purbeck  beds  ;  4.  Lower  jaw  and  teeth  of  Plagiaulax,  Pur- 
beck  beds.  All  the  figures  are  of  the  natural  size. 

Professor  Owen,  the  highest  living  authority  on  the  subject, 
Amphitherium  is  believed  to  be  a  small  Marsupial,  most 
nearly  allied  to  the  living  Banded  Ant-eater  (Myrmecobius)  of 
Australia  (fig.  158).  Amphilestes  and  Phascolotherium  (fig. 


262  HISTORICAL  PALEONTOLOGY. 

184)  are  also  believed  by  the  same  distinguished  anatomist 
and  palaeontologist  to  have  been  insect-eating  Marsupials,  and 
the  latter  is  supposed  to  find  its  nearest  living  ally  in  the 
Opossums  (Didelphys)  of  America.  Lastly,  the  Stereognathus 
of  the  Stonesfield  Slate  is  in  a  dubious  position.  It  may  have 
been  a  Marsupial;  but,  upon  the  whole,  Professor  Owen  is 
inclined  to  believe  that  it  must  have  been  a  hoofed  and  her- 
bivorous Quadruped  belonging  to  the  series  of  the  higher  Mam- 
mals (Placentalia).  In  the  Middle  Purbeck  beds,  near  to  the 
close  of  the  Oolitic  period,  we  have  also  evidence  of  the  exist- 
ence of  a  number  of  small  Mammals,  all  of  which  are  probably 
Marsupials.  Fourteen  species  are  known,  all  of  small  size, 
the  largest  being  no  bigger  than  a  Polecat  or  Hedgehog.  The 
genera  to  which  these  little  quadrupeds  have  been  referred  are 
Plagiaulax,  Spalacotherium,  Triconodon,  and  Galestes.  The 
first  of  these  (fig.  184,  4)  is  believed  by  Professor  Owen  to 
have  been  carnivorous  in  its  habits ;  but  other  authorities 
maintain  that  it  was  most  nearly  allied  to  the  living  Kangaroo- 
rats  (Hypsiprymnus}  of  Australia,  and  that  it  was  essentially 
herbivorous.  The  remaining  three  genera  appear  to  have 
been  certainly  insectivorous,  and  find  their  nearest  living  rep- 
resentatives in  the  Australian  Phalangers  and  the  American 
Opossums. 

Finally,  it  is  interesting  to  notice  in  how  many  respects  the 
Jurassic  fauna  of  Western  Europe  approached  to  that  now 
inhabiting  Australia.  At  the  present  day,  Australia  is  almost 
wholly  tenanted  by  Marsupials;  upon  its  land-surface  flourish 
Araucarice  and  Cycadaceous  plants,  and  in  its  seas  swim  the 
Port-Jackson  Shark  (Ccstracion  Philip  pi*)  ;  whilst  the  Mollus- 
can  genus  Trigonia  is  nowadays  exclusively  confined  to  the 
Australian  coasts.  In  England,  at  the  time  of  the  deposition 
of  the  Jurassic  rocks,  we  must  have  had  a  fauna  and  flora  very 
closely  resembling  what  we  now  see  in  Australia.  The  small 
Marsupials,  Amphitherium,  Phascolotherium,  and  others,  prove 
jhat  the  Mammals  were  the  same  in  order;  cones  of  Arau- 
carian  pines,  with  tree-ferns  and  fronds  of  Cycads,  occur 
throughout  the  Oolitic  series;  spine-bearing  fishes,  like  the 
Port-Jackson  Shark,  are  abundantly  represented  by  genera 
such  as  Acrodus  and  Strophodus;  and  lastly,  the  genus  Tri- 
gonia, now  exclusively  Australian,  is  represented  in  the  Oolites 
by  species  which  differ  little  from  those  now  existing.  More- 
over, the  discovery  during  recent  years  of  the  singularMud-fish, 
the  Ceratodus  Fosteri,  in  the  rivers  of  Queensland,  has  added 


THE  JURASSIC   PERIOD.  263 

another  and  a  very  striking  point  of  resemblance  to  those 
already  mentioned;  since  this  genus  of  Fishes,  though  pre- 
eminently Triassic,  nevertheless  extended  its  range  into  the 
Jurassic.  Upon  the  whole,  therefore,  there  is  reason  to  con- 
clude that  Australia  has  undergone  since  the  close  of  the 
Jurassic  period  fewer  changes  and  vicissitudes  than  any  other 
known  region  of  the  globe ;  and  that  this  wonderful  continent 
has  therefore  succeeded  in  preserving  a  greater  number  of 
the  characteristic  life-features  of  the  Oolites  than  any  other 
country  with  which  we  are  acquainted. 

LITERATURE. 

The  following  list  comprises  some  of  the  more  important 
sources  of  information  as  to  the  rocks  and  fossils  of  the  Juras- 
sic series  : — 

(1)  'Geology  of  Oxford  and  the  Thames  Valley.'   Phillips. 

(2)  '  Geology  of  Yorkshire, '  vol.  ii.     Phillips. 

(3)  '  Memoirs   of   the   Geological   Survey  of   Great   Britain. ' 

(4)  '  Geology  of  Cheltenham. '     Murchison,  2d  ed.  Buckman. 

(5)  '  Introduction   to   the   Monograph  of   the   Oolitic   Aster- 

iadas '    (Palaeontographical   Society).     Wright. 

(6)  "  Zone  of  Avicula  contorta  and  the  Lower  Lias  of  the 

South    of    England " — '  Quart.    Journ     Soc., '    vol.    xvi., 
1860.    Wright. 

(7)  "  Oolites    of    Northamptonshire " — '  Quart.    Journ.    Geol. 

Soc., '  vols.  xxvi.  and  xxix.     Sharp. 

(8)  '  Manual  of  Geology. '     Dana. 

(9)  '  Der  Jura. '     Quenstedt. 

(10)  'Das  Flotzgebirge  Wurttembergs. '  Quenstedt. 

(n)  'Jura  Formation.'     Oppel. 

(12)  '  Paleontologie  du  Departement  de  la  Moselle.'  Terquem. 

(13)  '  Cours  elementaire  de  Paleontologie.'    D'Orbigny. 

(14)  'Paleontologie  Franchise. '     D'Orbigny. 

(15)  'Fossil     Echinodermata     of     the     Oolitic     Formation.' 

(Palaeontographical  Society).     Wright. 

(16)  '  Brachiopoda     of     the     Oolitic     Formation'     (Palaeon- 

tographical  Society).     Davidson. 

(17)  '  Mollusca  of  the  Great  Oolite'   ( Palaeontographical  So- 

ciety).    Morris  and  Lycett. 

(18)  'Monograph  of  the  Fossil  Trigoniae*  (Palaeontographical 

Society).     Lycett. 

(19)  'Corals   of   the    Oolitic   Formation'    (Palaeontographical 

Society).     Edwards  and  Haime. 

(20)  '  Supplement   to    the    Corals    of    the    Oolitic    Formation ' 

(Palaeontographical  Society).     Martin  Duncan. 

(21)  'Monograph    of    the    Belemnitidae '     (Palaeontographical 

Society).     Phillips. 

(22)  'Structure   of   the   Belemnitidae'    (Mem.   Geol.    Survey). 

Huxley. 


264  HISTORICAL  PALAEONTOLOGY. 

(23)  '  Sur  les  Belemnites. '     Blainville. 

(24)  '  Cephalopoden. '     Quenstedt. 

(25)  '  Mineral  Conchology. '     Sowerby. 

(26)  'Jurassic   Cephalopoda'    ( Palaeontologica   Indica).   Waa- 

gen. 

(27)  'Manual  of  the  Mollusca. '     Woodward. 

(28)  '  Petrefaktenkunde. '     Schlotheim. 

(29)  '  Bridgewater  Treatise. '     Buckland. 

(30)  '  Versteinerungen   des   Oolithengebirges. '     Roemer. 

(31)  'Catalogue  of  British  Fossils.'    Morris. 

(32)  '  Catalogue  of  Fossils  in  the  Museum  of  Practical  Geol- 

ogy. '  Etheridge. 

(33)  '  Beitrage  zur  Petrefaktenkunde.'     Miinster. 

(34)  '  Petrefacta  Germanise. '     Goldfuss. 

(35)  '  Lethcea  Rossica. '     Eichwald. 

(36)  'Fossil    Fishes'    (Decades    of    the    Geol.    Survey).      Sir 

Philip  Egerton. 

(37)  '  Manual  of   Palaeontology. '     Owen. 

(38)  '  British  Fossil   Mammals  and  Birds. '     Owen. 

(39)' Monographs  of  the  Fossil  Reptiles  of  the  Oolitic  For- 
mation.' (Palseontographical  Society).  Owen. 

(40)  '  Fossil  Mammals  of  the  Mesozoic  Formations '  Palae- 
ontographical  Society).  Owen. 


(41)   'Catalogue  of  Ornithosauria. '     Seeley. 
(42) 


'  Classification  of  the  Deinosauria  " — '  Quart.  Journ.  Geol. 
Soc., '  vol.  xxvi.,  1870.     Huxley. 


CHAPTER  XVII. 
THE  CRETACEOUS  PERIOD. 

The  next  series  of  rocks  in  ascending  order  is  the  great  and 
important  series  of  the  Cretaceous  Rocks,  so  called  from  the 
general  occurrence  in  the  system  of  chalk  (Lat.  creta,  chalk). 
As  developed  in  Britain  and  Europe  generally,  the  following 
leading  subdivisions  may  be  recognized  in  the  Cretaceous 
series : — 

2.  Lowefcreensand  or  Neocomian,  }  Lower  Cretaceous. 

3.  Gault,  >, 

4.  Upper  Greensand,  TT  ^ 

5.  Chalk,  §  [  UPPer   Cretaceous. 

6.  Maestricht  beds, 

I.  Wealden. — The   Wealden  formation,  though  of  consider- 


THE  CRETACEOUS  PERIOD.  265 

able  importance,  is  a  local  group,  and  is  confined  to  the  south- 
east of  England,  France,  and  some  other  parts  of  Europe.  Its 
name  is  derived  from  the  Weald,  a  district  comprising  parts  of 
Surrey,  Sussex,  and  Kent,  where  it  is  largely  developed.  Its 
lower  portion,  for  a  thickness  of  from  500  to  1000  feet,  is 
arenaceous,  and  is  known  as  the  Hastings  Sands.  Its  Upper 
portion,  for  a  thickness  of  150  to  nearly  300  feet,  is  chiefly 
argillaceous,  consisting  of  clays  with  sandy  layers,  and  occa- 
sionally courses  of  limestone.  The  geological  importance  of 
the  Wealden  formation  is  very  great,  as  it  is  undoubtedly  the 
delta  of  an  ancient  river,  being  composed  almost  wholly  of 
fresh-water  beds,  with  a  few  brackish-water  and  even  marine 
strata,  intercalated  in  the  lower  portion.  Its  geographical 
extent,  though  uncertain,  owing  to  the  enormous  denudation 
to  which  it  has  been  subjected,  is  nevertheless  great,  since  it 
extends  from  Dorsetshire  to  France,  and  occurs  also  in  North 
Germany.  Still,  even  if  it  were  continuous  between  all  these 
points,  it  would  not  be  larger  than  the  delta  of  such  a  modern 
river  as  the  Ganges.  The  river  which  produced  the  Wealden 
series  must  have  flowed  from  an  ancient  continent  occupying 
what  is  now  the  Atlantic  Ocean ;  and  the  time  occupied  in 
the  formation  of  the  Wealden  must  have  been  very  great, 
though  we  have,  of  course,  no  data  by  which  we  can  accurately 
calculate  its  duration. 

The  fossils  of  the  Wealden  series  are,  naturally,  mostly  the 
remains  of  such  animals  as  we  know  at  the  present  day  as  in- 
habiting rivers.  We  have,  namely,  fresh-water  Mussels  (Unto), 
River-snails  (Paludina'),  and  other  fresh-water  shells,  with 
numerous  little  bivalved  Crustaceans,  and  some  fishes. 

II.  Lower  Greensand  (Niocomien  of  D'Orbigny). — The 
Wealden  beds  pass  upward,  often  by  insensible  gradations, 
into  the  Lower  Greensand.  The  name  Lower  Greensand  is 
not  an  appropriate  one,  for  green  sands  only  occur  sparingly 
and  occasionally,  and  are  found  in  other  formations.  For  this 
reason  it  has  been  proposed  to  substitute  for  Lower  Greensand 
the  name  Neocomian,  derived  from  the  town  of  Neufchatel — 
anciently  called  Neocomum — in  Switzerland.  If  this  name 
were  adopted,  as  it  ought  to  be,  the  Wealden  beds  would  be 
called  the  Lower  Neocomian. 

The  Lower  Greensand  or  Neocomian  of  Britain  has  a  thick- 
ness of  about  850  feet,  and  consists  of  alternations  of  sands, 
sandstones,  and  clays,  with  occasional  calcareous  bands.  The 
general  color  of  the  series  is  dark  brown,  sometimes  red;  and 


266  HISTORICAL  PALEONTOLOGY. 

the  sands  are  occasionally  green,  from  the  presence  of  silicate 
of  iron. 

The  fossils  of  the  Lower  Greensand  are  purely  marine,  and 
among  the  most  characteristic  are  the  shells  of  Cephalopoda. 

The  most  remarkable  point,  however,  about  the  fossils  of 
the  Lower  Cretaceous  series,  is  their  marked  divergence  from 
the  fossils  of  the  Upper  Cretaceous  rocks.  Of  280  species  of 
fossils  in  the  Lower  Cretaceous  series,  only  51,  or  about  18 
per  cent,  pass  on  into  the  Upper  Cretaceous.  This  break  in 
the  life  of  the  two  periods  is  accompanied  by  a  decided  phy- 
sical break  as  well;  for  the  Gault  is  often,  if  not  always,  un- 
conformably  superimposed  on  the  Lower  Greensand.  At  the 
same  time,  the  Lower  and  Upper  Cretaceous  groups  form  a 
closely-connected  and  inseparable  series,  as  shown  by  a  com- 
parison of  their  fossils  with  those  of  the  underlying  Jurassic 
rocks  and  the  overlying  Tertiary  beds.  Thus,  in  Britain  no 
marine  fossil  is  known  to  be  common  to  the  marine  beds  of 
the  Upper  Oolites  and  the  Lower  Greensand ;  and  of  more 
than  500  species  of  fossils  in  the  Upper  Cretaceous  rocks, 
almost  every  one  died  out  before  the  formation  of  the  lowest 
Tertiary  strata,  the  only  survivors  being  one  Brachiopod  and  a 
few  Foraminifera. 

III.  Gault   (Aptien  of  D'Orbigny). — The  lowest  member  of 
the    Upper    Cretaceous    series    is    a    stiff,    dark-grey,    blue,    or 
brown  clay,  often  worked  for  brick-making,  and  known  as  the 
Gault,    from    a    provincial    English    term.      It    occurs    chiefly    in 
the    southeast   of    England,   but    can   be    traced   through    France 
to  the  flanks  of  the  Alps  and  Bavaria.     It  never  exceeds   100 
feet    in    thickness;    but    it    contains    many    fossils,    usually    in    a 
state  of  beautiful  preservation. 

IV.  Upper  Greensand    (Albien  of  D'Orbigny;    Unterquader 
and  Lower  Planerkalk  of   Germany). — The  Gault  is   succeeded 
upward    by    the    Upper    Greensand,    which    varies    in    thickness 
from  3   up   to   100   feet,   and  which  derives   its   name   from   the 
occasional    occurrence   in   it   of   green   sands.     These,   however, 
are    local    and    sometimes    wanting,     and    the    name    "Upper 
Greensand"  is  to  be  regarded  as  a  name  and  not  a  description. 
The  group  consists,  in   Britain,   of  sands   and  clays,   sometimes 
with  bands  of  calcareous  grit  or  siliceous  limestone,  and  occa- 
sionally containing  concretions  of  phosphate  of  lime,  which  are 
largely  worked  for  agricultural  purposes. 

V.  White    Chalk. — The    top    of    the    Upper    Greensand    be- 
comes  argillaceous,   and  passes   up  gradually  into   the  base  of 


THE  CRETACEOUS  PERIOD.  267 

the  great  formation  known  as  the  true  Chalk,  divided  into 
the  three  subdivisions  of  the  chalk-marl,  white  chalk  without 
flints,  and  white  chalk  with  flints.  The  first  of  these  is  sim- 
ply argillaceous  chalk,  and  passes  up  into  a  great  mass  of 
obscurely-stratified  white  chalk  in  which  there  are  no  flints 
(Turonien  of  D'Orbigny;  Mittelquader  of  Germany).  This  in 
turn,  passes  up  into  a  great  mass  of  white  chalk,  in  which  the 
stratification  is  marked  by  nodules  of  black  flint  arranged  in 
layers  (Sffnonien  of  D'Orbigny;  Oberquadcr  of  Germany).  T.h* 
thickness  of  these  three  subdivisions  taken  together  is  some 
times  over  1000  feet,  and  their  geographical  extent  is  ven 
great.  White  Chalk,  with  its  characteristic  appearance,  may 
be  traced  from  the  north  of  Ireland  to  the  Crimea,  a  distance 
of  about  1 140  geographical  miles ;  and,  in  an  opposite  direction, 
from  the  south  of  Sweden  to  Bordeaux,  a  distance  of  about 
840  geographical  miles. 

VI.  In  Britain  there  occur  no  beds  containing  Chalk  fossils, 
or  in  any  way  referable  to  the  Cretaceous  period,  above  the 
true  White  Chalk  with  flints.  On  the  banks  of  the  Maes, 
however,  near  Maestricht  in  Holland,  there  occurs  a  series  of 
yellowish  limestones,  of  about  100  feet  in  thickness,  and  un- 
doubtedly superior  to  the  White  Chalk.  These  Maestricht 
beds  (Danien  of  D'Orbigny)  contain  a  remarkable  series  of 
fossils,  the  characters  of  which  are  partly  Cretaceous  and 
partly  Tertiary.  Thus,  with  the  characteristic  Chalk  fossils, 
Belemnites,  Baculites,  Sea-urchins,  &c.,  are  numerous  Univalves 
Molluscs,  such  as  Cowries  and  Volutes,  which  are  otherwise 
exclusively  Tertiary  or  Recent. 

Holding  a  similar  position  to  the  Maestricht  beds,  and 
showing  a  similar  intermixture  of  Cretaceous  forms  with  later 
types,  are  certain  beds  which  occur  in  the  island  of  Seeland, 
in  Denmark,  and  which  are  known  as  the  Fax'oe  Limestone. 

Of  a  somewhat  later  date  than  the  Maestricht  beds  is  the 
Pisolitic  Limestone  of  France,  which  rests  unconformably  on 
the  White  Chalk,  and  contains  a  large  number  of  Tertiary 
fossils  along  with  some  characteristic  Cretaceous  types. 

The  subjoined  sketch-section  exhibits  the  general  succession 
of  the  Cretaceous  deposits  in  Britain : — 


268 


HISTORICAL  PALAEONTOLOGY. 


GENERALIZED  SECTION  OF  THE  CRETACEOUS  SERIES 
OF  BRITAIN. 

Fig.  185. 


Eocene. 


White  Chalk  with  Flints. 


-  White  Chalk  without  Flints. 

..  Chalk  Marl. 

...  Upper  Greensand. 

~  Gault. 


Lower      Greensand      or 
Neocomian. 


Wreald  Clay. 

> .,  Wealden  Series. 

Hastings  Sands. 


In  North  America,  strata  of  Lower  Cretaceous  age  are  well 
represented  in  Missouri,  Wyoming,  Utah,  and  in  some  other 
areas ;  but  the  greater  portion  of  the  American  deposits  of 
this  period  are  referable  to  the  Upper  Cretaceous.  The  rocks 


THE  CRETACEOUS  PERIOD.  269 

of  this  series  are  mostly  sands,  clays,  and  limestones — Chalk 
itself  being  unknown  except  in  Western  Arkansas.  Amongst 
the  sandy  accumulations,  one  of  the  most  important  is  the  so- 
called  "  marl "  of  New  Jersey,  which  is  truly  a  "  Greensand, " 
and  contains  a  large  proportion  of  glauconite  (silicate  of  iron 
and  potash).  It  also  contains  a  little  phosphate  of  lime,  and  is 
largely  worked  for  agricultural  purposes.  The  greatest  thick- 
ness attained  by  the  Cretaceous  rocks  of  North  America  is 
about  9000  feet,  as  in  Wyoming,  Utah,  and  Colorado.  Ac- 
cording to  Dana,  the  Cretaceous  rocks  of  the  Rocky  Mountain 
territories  pass  upwards  "  without  interruption  into  a  coal- 
bearing  formation,  several  thousand  feet  thick,  on  which  the 
following  Tertiary  strata  lie  unconformably.  "  The  lower  por- 
tion of  this  "  Lignitic  formation "  appears  to  be  Cretaceous, 
and  contains  one  or  more  beds  of  Coal ;  but  the  upper  part  of  it 
perhaps  belongs  to  the  Lower  Tertiary.  In  America,  therefore, 
the  lowest  Tertiary  strata  appear  to  rest  conformably  upon  the 
highest  Cretaceous ;  whereas  in  Europe,  the  succession  at  this 
point  is  invariably  an  unconformable  one.  Owing,  however,  to 
the  fact  that  the  American  "  Lignitic  formation  "  is  a  shallow- 
water  formation,  it  can  hardly  be  expected  to  yield  much 
material  whereby  to  bridge  over  the  great  palaeontological  gap 
between  the  White  Chalk  and  Eocene  in  the  Old  World. 

Owing  to  the  fact  that  so  large  a  portion  of  the  Cretaceous 
formation  has  been  deposited  in  the  sea,  much  of  it  in  deep 
water,  the  plants  of  the  period  have  for  the  most  part  been 
found  special  members  of  the  series,  such  as  the  Wealden  beds, 
the  Aix-la-Chapelle  sands,  and  the  Lignitic  beds  of  North 
America.  Even  the  purely  marine  strata,  however,  have 
yielded  plant  remains,  some  of  these  are  peculiar  and 
proper  to  the  deep-sea  deposits  of  the  series.  Thus  the  little 
calcareous  discs  termed  "  coccoliths, "  which  are  known  to  be 
of  the  nature  of  calcareous  sea-weeds  (Alga}  have  been  de- 
tected in  the  White  Chalk;  and  the  flints  of  the  same  forma- 
tion commonly  contain  the  spore-cases  of  the  microscopic 
Desmids  (the  so-called  Xanthidia),  along  with  the  siliceous  cases 
of  the  equally  diminutive  Diatoms. 

The  plant-remains  of  the  Lower  Cretaceous  greatly  resemble 
those  of  the  Jurassic  period,  consisting  mainly  of  Ferns,  Cy- 
cads,  and  Conifers.  The  Upper  Cretaceous  rocks,  however, 
both  in  Europe  and  in  North  America,  have  yielded  an  abun- 
dant flora  which  resembles  the  existing  vegetation  of  the  globe 
in  consisting  mainly  of  Angiospermous  Exogens  and  of  Mono- 


270  HISTORICAL  PALAEONTOLOGY. 

cotyledons.  *  In  Europe  the  plant-remains  in  question  have 
been  found  chiefly  in  certain  sands  in  the  neighborhood  of  Aix- 
la-Chapelle,  and  they  consist  of  numerous  Ferns,  Conifers  (such 
as  Cycadopteris},  Screw  Pines  (Pandanus),  Oaks  (Quercus), 
Walnut  (Juglans},  Fig.  (Ficus},  and  many  Proteacea,  some  of 
which  are  referred  to  existing  genera  (Dryandra,  Banksia, 
Grevillea,  &c.) 

In  North  America,  the  Cretaceous  strata  of  New  Jersey, 
Alabama,  Nebraska,  Kansas,  &c.,  have  yielded  the  remains  of 
numerous  plants,  many  of  which  belong  to  existing  genera. 
Amongst  these  may  be  mentioned  Tulip-trees  (Liriodendron), 
Sassafras  (fig.  186),  Oaks  (Quercus),  Beeches  (Fagus*),  Plane- 
trees  (Platanus},  Alders  (Alnus),  Dog-wood  (Cornus},  Willows 
(Salix),  Poplars  (Populus},  Cypresses  (Cupressus},  Bald  Cy- 
presses (Tax odium},  Magnolias,  &c.  Besides  these,  however, 
there  occur  other  forms  which  have  now  entirely  disappeared 
from  North  America — as,  for  example,  species  of  Cinnamomum 
and  Araucaria. 

It  follows  from  the  above,  that  the  Lower  and  Upper  Creta- 
ceous rocks  are,  from  a  botanical  point  of  view,  sharply  sepa- 
rated from  one  another.  The  Palaeozoic  period,  as  we  have 
seen,  is  characterized  by  the  prevalence  of  "  Flowerless "  plants 
(Cryptogams},  its  higher  vegetation  consisting  almost  exclu- 
sively of  Conifers.  The  Mesozoic  period,  as  a  whole,  is  charac- 
terized by  the  prevalence  of  the  Cryptogamic  group  of  the 
Ferns,  and  the  Gymnospermic  groups  of  the  Conifers  and  the 
Cycads.  Up  to  the  close  of  the  Lower  Cretaceous,  no  Angio- 
spermous  Exogens  are  certainly  known  to  have  existed,  and 
Monocotyledonous  plants  or  Endogens  are  very  poorly  repre- 
sented. WTith  the  Upper  Cretaceous,  however,  a  new  era  of 
plant-life,  of  which  our  present  is  but  the  culmination,  com- 
menced, with  a  great  and  apparently  sudden  development  of  new 
forms.  In  place  of  the  Ferns,  Cycads,  and  Conifers  of  the  earlier 

*  The  "  Flowering  plants  "  are  divided  into  the  two  great  groups  of 
the  Endogens  and  Exogens.  The  Endogens  (such  as  Grasses,  Palms,  Lilies, 
&c.)  have  no  true  bark,  nor  rings  of  growth,  and  the  stem  is  said  to  be 
"  endogenous ;"  the  young  plant  also  possesses  but  a  single  seed-leaf  or 
"cotyledon."  Hence" these  plants  are  often  simply  called  "Monocotyledons." 
The  Exogens,  on  the  other  hand,  have  a  true  bark ;  and  the  stem  increases 
by  annual  additions  to  the  outside,  so  that  rings  of  growth  are  produced. 
The  young  plant  has  two  seed-leaves  or  "  cotyledons,"  and  these  plants 
are  therefore  called  "  Dicotyledons."  Amongst  the  Exogens,  the  Pines 
(Conifers')  and  the  Cycads  have  seeds  which  are  unprotected  by  a  seed- 
vessel,  and  they  are  therefore  called  "Gymnosperms"  All  the  other  Exo- 
gens, including  the  ordinary  trees,  shrubs,  and  flowering  plants,  have  the 
seeds  enclosed  in  a  seed-vessel,  and  are  therefore  called  "  Angiosperms." 
The  derivation  of  these  terms  will  be  found  in  the  Glossary  at  the  end  of 
the  volume. 


THE  CRETACEOUS  PERIOD. 


271 


Mesozoic  deposits,  we  have  now  an  astonishingly  large  number 
of  true  Angiospermous  Exogens,  many  of  them  belonging  to 
existing  types;  and  along  with  these  are  various  Monocotyle- 
donous  plants,  including  the  first  examples  of  the  great  and  im- 
portant group  of  the  Palms.  It  is  thus  a  matter  of  interest  to 
reflect  that  plants  closely  related  to  those  now  inhabiting  the 
earth,  were  in  existence  at  a  time  when  the  ocean  was  tenanted 
by  Ammonites  and  Belemnites,  and  when  land  and  sea  and 
air  were  peopled  by  the  extraordinary  extinct  Reptiles  of  the 
Mesozoic  period. 

As  regards  animal  life,  the  Protozoans  of  the   Cretaceous 
period  are  exceedingly  numerous,  and  are  represented  by  Fora- 


?.  186. — Cretaceous  Angiosperms.     a.  Sassafras  Cretaceum;    b,  Liriodendron 
Meekii;  c,  Leguminositea  Marcouanus;  d,  Salix  Meekii.    (After  Dana.) 

minifera  and  Sponges.  As  we  have  already  seen,  the  White 
Chalk  itself  is  a  deep-sea  deposit,  almost  entirely  composed 
of  the  microscopic  shells  of  Foraminifers,  along  with  Sponge- 
spicules,  and  organic  debris  of  different  kinds  (see  p.  23,  fig.  7). 
The  green  grains  which  are  abundant  in  several  minor  sub- 


272  HISTORICAL  PALEONTOLOGY. 

divisions  of  the  Cretaceous,  are  also  in  many  instances  really 
casts  in  glauconite  of  the  chambered  shells  of  these  minute 
organisms.  A  great  many  species  of  Foraminifera  have  been 
recognized  in  the  Chalk ;  but  the  three  principal  genera  are 


Fig.  187. — Rotalia  Boueana. 

Globigerina,  Rotalia  (fig.  187),  and  Textularia — groups  which 
are  likewise  characteristic  of  the  "ooze"  of  the  Atlantic  and 
Pacific  Oceans  at  great  depths.  The  flints  of  the  Chalk  also 
commonly  contain  the  shells  of  Foraminifera.  The  Upper 
Greensand  has  yielded  in  considerable  numbers  the  huge 
Foraminifera  described  by  Dr.  Carpenter  under  the  name  of 
Parkeria,  the  spherical  shells  of  which  are  composed  of  sand- 
grains  agglutinated  together,  and  sometimes  attain  a  diameter 
of  two  and  a  quarter  inches.  The  Cretaceous  Sponges  are 
extremely  numerous,  and  occur  under  a  great  number  of  varie- 
ties of  shape  and  structure ;  but  the  two  most  characteristic 
genera  are  Siphonia  and  Ventriculites,  both  of  which  are  ex- 
clusively confined  to  strata  of  this  age.  The  Siphonia  (fig. 
188)  consist  of  a  pear-shaped,  sometimes  lobed  head,  supported 
by  a  longer  or  shorter  stem,  which  breaks  up  at  its  base  into  a 
number  of  root-like  processes  of  attachment.  The  water  gained 
access  to  the  interior  of  the  Sponge  by  a  number  of  minute 
openings  covering  the  surface,  and  ultimately  escaped  by  a 
single,  large,  chimney-shaped  aperture  at  the  summit.  In  some 
respects  these  sponges  present,  a  singular  resemblance  to  the 
beautiful  "  Vitreous  Sponges "  (Holtenia  or  Pheronema}  of  the 
deep  Atlantic ;  and,  like  these,  they  were  probably  denizens 
of  a  deep  sea.  The  Ventriculites  of  the  Chalk  (fig.  189)  is, 
however,  a  genus  still  more  closely  allied  to  the  wonderful 
flint  Sponges,  which  have  been  shown,  by  the  researches  of 
the  Porcupine,  Lightning,  and  Challenger  expeditions,  to  live 
half  buried  in  the  calcareous  ooze  of  the  abysses  of  our  great 
oceans.  Many  forms  of  this  genus  are  known,  having  "usu- 
ally the  form  of  graceful  vases,  tubes,  or  funnels,  variously 


THE  CRETACEOUS  PERIOD. 


273 


ridged  or  grooved,  or  otherwise  ornamented  on  the  surface, 
frequently  expanded  above  into  a  cup-like  lip,  and  continued 
below  into  a  bundle  of  fibrous  roots.  The  minute  structure  of 
these  bodies  shows  an  extremely  delicate  tracery  of  fine  tubes, 
sometimes  empty,  sometimes  filled  with  loose  calcareous  mat- 
ter dyed  with  peroxide  of  iron.  " — (Sir  Wyville  Thomson.) 
Many  of  the  Chalk  sponges,  originally  calcareous,  have  been 
converted  into  flint  subsequently;  but  the  Ventriculites  are 
really  composed  of  this  substance,  and  are  therefore  genuine 
"  Siliceous  Sponges, "  like  the  existing  Venus's  Flower-basket 
(Euplectella}.  Like  the  latter,  the  skeleton  was  doubtless  orig- 
inally composed,  in  the  young  state,  of  disconnected  six- 
rayed  spicules,  which  ultimately  become  fixed  together  to 
constitute  a  continuous  frame-work.  The  sea-water,  as  in  the 
recent  forms,  must  have  been  admilted  to  the  interior  of  the 
Sponge  by  numerous  apertures  on  its  exterior,  subsequently 
escaping  by  a  single  large  opening  at  its  summit. 


Fig.    ISS.—Sipfionia  flcu». 
Upper  Greensand,  Europe. 


Fig.  ISQ.—VentricuUtes  simplex. 
White  Chalk,  Britain. 


Amongst    the    Ccelentcrates,   the    "  Hydroid    Zoophytes "   are 
represented  by  a   species   of   the   encrusting  genus   Hydractinia, 
the    horny    polypary    of    which    is    so   commonly    found    at    the 
18 


274 


HISTORICAL  PALEONTOLOGY. 


present  day  adhering  to  the  exterior  of  shells.  The  occurrence 
of  this  genus  is  of  interest,  because  it  is  the  first  known  instance 
in  the  entire  geological  series  of  the  occurrence  of  an  unques- 


Flg.  IQO.—Synfielia  Sharpeana.    Chalk,  England. 

tionable  Hydroid  of  a  modern  type,  though  many  of  the  exist- 
ing forms  of  these  animals  possess  structures  which  are  per- 
fectly fitted  for  preservation  in  the  fossil  condition.  The  corals 
of  the  Cretaceous  series  are  not  very  numerous,  and  for  the 
most  part  are  referable  to  types  such  as  Trochocyathus,  Stephano- 
pliyllia,  Parasmilia,  Synhelia  (fig.  190),  &c.,  which  belong  to 
the  same  great  group  of  corals  as  the  majority  of  existing 
forms.  We  have  also  a  few  "Tabulate  Corals"  (Polytre- 
macis),  hardly,  if  at  all,  generically  separable  from  very  ancient 
forms  (Heliolites)  ;  and  the  Lower  Greensand  has  yielded  the 
remains  of  the  little  Plolocystis  elegans,  long  believed  to  be  the 
last  of  the  great  Palaeozoic  group  of  the  Rugosa. 

As  regards  the  Echinoderms,  the  group  of  the  Crinoids  now 
exhibits  a  marked  decrease  in  the  number  and  variety  of  its 
types.  The  "  stalked "  forms  are  represented  by  Pentacrinus 
and  Bourgueticrinus,  and  the  free  forms  by  Feather-stars  like 
our  existing  Comatulce;  whilst  a  link  between  the  stalked  and 
free  groups  is  constituted  by  the  curious  "  Tortoise  Encrinite 
(Marsupites).  By  far  the  most  abundant  Cretaceous  Echino- 
derms, however,  are  Sea-urchins  (Echinoids)  ;  though  several 
Star-fishes  are  known  as  well.  The  remains  of  Sea-urchins  are 
so  abundant  in  various  parts  of  the  Cretaceous  series,  especially 
in  the  White  Chalk,  and  are  often  so  beautifully  preserved, 


THE  CRETACEOUS  PERIOD. 


275 


that  they  constitute  one  of  the  most  marked  features  of  the 
fauna  of  the  period.  From  the  many  genera  of  Sea-urchins 
which  occur  in  strata  of  this  age,  it  is  difficult  to  select  char- 
acteristic types;  but  the  genera  Galerites  (fig.  191),  Discoidea 
(fig.  192),  Micraster,  Ananchytes,  Diadema,  Salenia,  and  Ci- 
daris,  may  be  mentioned  as  being  all  important  Cretaceous 
groups. 

Coming  to  the  Annulose  Animals  of  the  Cretaceous  period, 
there  is  little  special  to  remark.  The  Crustaceans  belong  for 
the  most  part  to  the  highly-organized  groups  of  the  Lobsters 


Fig.  191. — Galerites  albogalerw,  viewed  from  below,  from  the  side,  and  from  above. 
White  Chalk. 

and  the  Crabs  (the  Macrurous  and  Brachyurous  Decapods)  ; 
but  there  are  also  numerous  little  Ostracodes,  especially  in  the 
fresh-water  strata  of  the  Wealden.  It  should  further  be  noted 


Fig.  192. — Discoidea  cylindrica;  under,  side,  and  upper  aspect. 
Upper  Greensand. 

that  there  occurs  here  a  great  development  of  the  singular 
Crustaceans  family  of  the  Barnacles  (Lepadida},  whilst  the  allied 
family  of  the  equally  singular  Acorn-shells  (Balanida}  is  feebly 
represented  as  well. 

Passing  on  to  the  Mollusca,  the  class  of  the  Sea-mats  arid 
Sea-mosses  (Polysoa)  is  immensely  developed  in  the  Cretaceous 
period,  nearly  two  hundred  species  being  known  to  occur  in 
the  Chalk.  Most  of  the  Cretaceous  forms  belong  to  the  family 


276 


HISTORICAL  PALEONTOLOGY. 


of  the  Escharidce,  the  genera  Eschar  a  and  Escharina  (fig.  193) 
being  particularly  well  represented.  Most  of  the  Cretaceous 
Polyzoans  are  of  small  size,  but  some7  attain  considerable  di- 
mensions, and  many  simulate  Corals  in  their  general  form  and 
appearance. 

The  Lamp-shells  (Brachiopods)  have  now  reached  a  further 
stage  of  the  progressive  decline,  which  they  have  been  under- 
going ever  since  the  close  of 
the  Palaeozoic  period.  Though 
individually  not  rare,  especially 
in  certain  minor  subdivisions 
of  the  series,  the  number  of 
generic  types  has  now  be- 
come distinctly  diminished,  the 
principal  forms  belonging  to 
the  genera  Terebratula,  Tere- 
bratella  (fig.  194),  Terebratulina, 
Rhynchonella,  and  Crania  (fig. 
195).  In  the  last  mentioned 


193.— A  small  fragment  of  Escharina 
Oceani,  of  the  natural  size  ;  and  a  portion 


of  the  same  enlarged.  Upper  Greensand.      of    these>    the    shdl    {s    attached 

to  foreign  bodies  by  the  sub- 
stance of  one  of  the  valves  (the  ventral),  whilst  the  other  or 
free  valve  is  more  or  less  limpet-shaped.  All  the  above-men- 
tioned genera  are  in  existence  at  the  present  day;  and  one 
species — namely,  Terebratulina  striata — appears  to  be  undis- 
tinguishable  from  one  now  living — the  Terebratulina  caput- 
serpentis. 

Whilst   the   Lamp-shells   are   slowly   declining,   the    Bivalves 
(Lamellibranchs}    are   greatly   developed,   and   are   amongst   the 


.  194.—  Terebratella  Astieriana.    Gault. 


most    abundant    and    characteristic    fossils    of    the    Cretaceous 
period.     In  the  great  river-deposit  of  the  Wealden,  the  Bivalves 


THE  CRETACEOUS  PERIOD. 


277 


are  forms  proper  to  fresh  water,  belonging  to  the  existing 
River-mussels  (Unio},  Cyrena  and  Cyclas;  but  most  of  the 
Cretaceous  Lamellibranchs  are  marine.  Some  of  the  most 


Fig.  195.  -Crania  lanabergensis.  The  left-hand  figure  shows  the  perfect  shell,  at- 
tached by  its  ventral  valve  to  a  foreign  body  ;  the  middle  figure  shows  the  exterior  of 
the  limpet-shaped  dorsal  valve  ;  and  the  right-band  figure  represents  the  Interior  of 
the  attached  valve.  White  Chalk. 


abundant  and  characteristic  of  these  belong  to  the  great  family 
of  the  Oysters  (Ostreidce).  Amongst  these  are  the  genera 
Gryphcea  and  Exogyra,  both  of  which  we  have  seen  to  occur 


Fig.  196.— Ostrea  Couloni.    Lower  Greensand, 

abundantly  in  the  Jurassic ;  and  there  are  also  numerous  true 
Oysters  (Ostrea,  fig.  196)  and  Thorny  Oysters  (Spondylus,  fig. 
197).  The  genus  Trigonia,  so  characteristic  of  the  Mesozoic 
deposits  in  general,  is  likewise  well  represented  in  the  Creta- 
ceous strata.  No  single  genus  of  Bivalves  is,  however,  so  highly 
characteristic  of  the  Cretaceous  period  as  Inoceramus,  a  group 
belonging  to  the  family  of  the  Pearl-mussels  (Aviculida) .  The 
shells  of  this  genus  (fig.  198)  have  the  valves  unequal  in  size, 


278  HISTORICAL  PALAEONTOLOGY. 

the  larger  valve  often  being  much  twisted,  and  both  valves 
being  marked  with  radiating  ribs  or  concentric  furrows.  The 
hinge-line  is  long  and  straight,  with  numerous  pits  for  the 
attachment  of  the  ligament  which  serves  to  open  the  shell. 
Some  of  the  Inocerami  attain  a  length  of  two  or  three  feet,  and 
fragments  of  the  shell  are  often  found  perforated  by  boring 


Fig.  19T.—Spondylu8Spinosu8.    White  Chalk. 

Sponges.  Another  extraordinary  family  of  Bivalves,  which  is 
exclusively  confined  to  the  Cretaceous  rocks,  is  that  of  the 
Hippuritida.  All  the  members  of  this  group  (fig.  199)  were 


Fig.  198.— Inoceramus  sulcatus.    Gault. 

attached  to  foreign  objects,  and  lived  associated  in  beds,  like 
Oysters.  The  two  valves  of  the  shell  are  always  altogether 
unlike  in  sculpturing,  appearance,  shape,  and  size ;  and  the 
cast  of  the  interior  of  the  shell  is  often  extremely  unlike  the 
form  of  the  outer  surface.  The  type-genus  of  the  family  is 
Hippurites  itself  (fig.  199),  in  which  the  shell  is  in  the  shape  of 
a  straight  or  slightly-twisted  horn,  sometimes  a  foot  or  more  in 
length,  constituted  by  the  attached  lower  valve,  and  closed 
above  by  a  small  lid-like  free  upper  valve.  About  a  hundred 
species  of  the  family  of  the  Hippuritida  are  known,  all  of  these 
being  Cretaceous,  and  occurring  in  Britain  (one  species  only), 
in  Southern  Europe,  the  West  Indies,  North  America,  Algeria, 


THE  CRETACEOUS  PERIOD. 


279 


and  Egypt.  Species  of  this  family  occur  in  such  numbers  in 
certain  compact  marbles  in  the  south  of  Europe,  of  the  age  of 
the  Upper  Cretaceous  (Lower  Chalk),  as  to  have  given  orgin 
to  the  name  of  "  Hippurite  Limestones, "  applied  to  these 
strata. 


Fig.  199. — Hippuritea  Toucasiana. 
A  large  individual,  with  two  smaller 
ones  attached  to  it.  Upper  Cretace- 
ous. South  of  Europe. 


Tig.  200.—  Valuta  elongata. 
White  Chalk. 


The  Univalves  (Caster o pods')  of  the  Cretaceous  period  are 
not  very  numerous,  nor  particularly  remarkable.  Along  with 
species  of  the  persistent  genus  Pleurotcmaria  and  the  Meso- 
zoic  Nerinaa,  we  meet  with  examples  of  such  modern  types 
as  Turritella  and  Natica,  the  Staircase-shells  (Solarium},  the 
Wentle-traps  (Scalaria),  the  Carrier-shells  (Phorus),  &c.  To- 
wards the  close  of  the  Cretaceous  period,  and  especially  in 
such  transitional  strata  as  the  Maestricht  beds,  the  Faxoe 


280 


HISTORICAL  PALAEONTOLOGY. 


Limestone,  and  the  Pisolitic  Limestone  of  France,  we  meet 
with  a  number  of  carnivorous  ("  siphonostomatous ")  Uni- 
valves, in  which  the  mouth  of  the  shell  is  notched  or  pro- 
duced into  a  canal.  Amongst  these  it  is  interesting  to 
recognize  examples  of  such  existing  genera  as  the  Volutes 
(Valuta,  fig.  200),  the  Cowries  (Cyprcca},  the  Mitre-shells 
(Mitra},  the  Wing-shells  (Strombus),  the  Scorpion-shells 
(Pleroceras},  &c. 

Upon  the  whole,  the  most  characteristic  of  all  the  Creta- 
ceous Molluscs  are  the  Cephalopods,  represented  by  the  remains 
of  both  Tetrabranchiate  and  Dibranchiate  forms.  Amongst  the 
former,  the  long-lived  genus  Nautilus  (fig.  201)  again  reap- 
pears, with  its  involute  shell,  its  capacious  body-chamber,  its 
simple  septa  between  the  air-chambers,  and  its  nearly  or  quite 
central  siphuncle.  The  majority  of  the  chambered  Cephalo- 
pods of  the  Cretaceous  belong,  however,  to  the  complex  and 
beautiful  family  of  the  Ammonitida ,  with  their  elaborately 
folded  and  lobed  septa  and  dorsally-placed  siphuncle.  This 


Fig.  201.— Different  views  of  Nautilus  Danicug.    Faxoe  Limestone 
(Upper  Cretaceous),  Denmark. 

family  disappears  wholly  at  the  close  of  the  Cretaceous  period ; 
but  it  approaching  extinction,  so  far  from  being  signalized  by 
any  slow  decrease  and  diminution  in  the  number  of  specific 
or  generic  types,  seems  to  have  been  attended  by  the  develop- 
ment of  whole  series  of  new  forms.  The  genus  Ammonites 
itself,  dating  from  the  Carboniferous,  has  certainly  passed  its 
prime,  but  it  is  still  represented  by  many  species,  and  some  of 
these  attained  enormous  dimensions  (two  or  three  feet  in 
diameter).  The  genus  Ancyloceras  (fig.  202),  though  likewise 
of  more  ancient  origin  (Jurassic),  is  nevertheless  very  charac- 


THE  CRETACEOUS  PERIOD. 


281 


teristic  of  the  Cretaceous.  In  this  genus  the  first  portion  of 
the  shell  is  in  the  form  of  a  flat  spiral,  the  coils  of  which  are 
not  in  contact ;  and  its  last  portion  is  produced  at  a  tangent, 
becoming  ultimately  bent  back  in  the  form  of  a  crosier.  Be- 


Fig.  202.—  Ancyloceras  Matheronianus .    Gault. 


sides  these  pre-existent  types,  the  Cretaceous  rocks  have 
yielded  a  great  number  of  entirely  new  forms  of  the  Ammoni- 
tidcc,  which  are  not  known  in  any  deposits  of  earlier  or  later 
date.  Amongst  the  more  important  of  these  may  be  men- 
tioned Crioccras,  Turrilites,  Scaphites,  Hamites,  Ptychoceras, 
and  Baculites.  In  the  genus  Crioceras  (fig.  204,  d),  the  shell 
consists  of  an  open  spiral,  the  volutions  of  which  are  not  in 
contact,  thus  resembling  a  partially-unrolled  Ammonite  or  the 
inner  portion  of  an  Ancyloceras.  In  Turrilites  (fig.  203),  the 
shell  is  precisely  like  that  of  the  Ammonite  in  its  structure ; 
but  instead  of  forming  a  flat  spiral,  it  is  coiled  into  an  ele- 
vated turreted  shell,  the  whorls  of  which  are  in  contact  with 
one  another.  In  the  genus  Scaphites  (fig.  204,  tf),  the  shell 
resembles  that  of  Ancyloceras  in  consisting  of  a  series  of  volu- 
tions coiled  into  a  flat  spiral,  the  last  being  detached  from  the 
others,  produced,  and  ultimately  bent  back  in  the  form  of  a 
crosier;  but  the  whorls  of  the  enrolled  part  of  the  shell  are  in 
contact,  instead  of  being  separate  as  in  the  latter.  In  the 
genus  Hamites  (fig.  204,  /),  the  shell  is  an  extremely  elongated 
cone,  which  is  bent  upon  itself  more  than  once,  in  a  hook-like 
manner,  all  the  volution  being  separate.  The  genus  Ptycho- 
ceras (fig.  204,  a)  is  very  like  Hamites,  except  that  the  shell  is 
only  bent  once ;  and  the  two  portions  thus  bent  are  in  contact 
with  one  another.  Lastly,  in  the  genus  Baculites  (fig.  201,  b 
and  c)  the  shell  is  simply  a  straight  elongated  cone,  not  bent 
in  any  way,  but  possessing  the  folded  septa  which  characterize 
the  whole  Ammonite  family.  The  Baculite  is  the  simplest  of 
all  the  forms  of  the  Ammonitida;  and  all  the  other  forms,  how- 


282 


HISTORICAL  PALAEONTOLOGY. 


ever  complex,  may  be  regarded  as  being  simply  produced  by 
the  bending  or  folding  of  such  a  conical  septate  shell  in  differ- 
ent ways.  The  Baculite,  therefore,  corresponds,  in  the  series 


Fig,  203. — Turrilites  cate- 
natus.  The  lower  figure  rep- 
resents the  entire  shell ;  the 
upper  figure  represents  the 
base  of  the  shell  seen  from 
below.  Gault. 


Fig.  20-t. — a,  Ptychoceraa  Emericianum,  reduced 
—Lower  Greensand ;  6,  Baculites  anceps,  reduced 
—Chalk  ;  c,  Portion  of  the  same,  showing  the  folded 
edges  of  the  septa  ;  d,  Crioceras  crittatum,  reduced 
—Gault ;  e,  Scaphite*  cequalis,  natural  size — Chalk  ; 
/,  Hamites  rotundus,  restored. — Gault. 


of  the  Ammonitidce,  to  the  Orthoceras  in  the  series  of  the  Nau- 
tilidce.  All  the  above-mentioned  genera  are  characteristically, 
or  exclusively,  Cretaceous,  and  they  are  accompanied  by  a 


THE  CRETACEOUS  PERIOD.  283 

number  of  other  allied  forms,  which  cannot  be  noticed  here. 
Not  a  single  one  of  these  genera,  further,  has  hitherto  been 
detected  in  any  strata  higher  than  the  Cretaceous.  We  may 
therefore  consider  that  these  wonderful,  varied,  and  elaborate 
forms  of  Ammonitidce  constitute  one  of  the  most  conspicuous 
features  in  the  life  of  the  Chalk  period. 

The  Dibranchiate  Cephalopods  are  represented  partly  by  the 
beak-like  jaws  of  unknown  species  of  Cuttle-fishes  and  partly 
by  the  internal  skeletons  of  Belemnites.  Amongst  the  latter, 
the  genus  Belemnites  itself  holds  its  place  in  the  lower  part  of 
the  Cretaceous  series;  but  it  disappears  in  the  upper  portion 
of  the  series,  and  its  place  is  taken  by  the  nearly-allied  genus 
Belemnitella  (fig.  205),  distinguished  by  the  possession  of  a 
straight  fissure  in  the  upper  end  of  the  guard.  This 
also  disappears  at  the  close  of  the  Cretaceous 
period;  and  no  member  of  the  great  Mesozoic 
family  of  the  Belemnitidcs  has  hitherto  been  dis- 
covered in  any  Tertiary  deposit,  or  is  known  to 
exist  at  the  present  day. 

Passing  on  next  to  the  Vertebrate  Animals  oi  the 
Cretaceous  period,  we  find  the  Fishes  represented 
as  before  by  the  Ganoids  and  the  Placoids,  to  which, 
however,  we  can  now  add  the  first  known  examples 
of  the  great  group  of  the  Bony  Fishes  or  Teleosteans, 
comprising  the  great  majority  of  existing  forms. 
The  Ganoid  Fishes  of  the  Cretaceous  (Lepidotus, 
Pycnodus,  &c.)  present  no  features  of  special  in- 
terest. Little,  also,  need  be  said  about  the  Placoid 
fishes  of  this  period.  As  in  the  Jurassic  deposits,  Fig.  205.— 
the  remains  of  these  consist  partly  of  the  teeth  of  2»JS«Ha  mu- 


genuine  Sharks  (Lamna,Odontaspis,  &c.),and  partly 
of  the  teeth  and  defensive  spines  of  Cestracionts, 
such  as  the  living  Port-Jackson  Shark.  The  pointed  and  sharp- 
edged  teeth  of  true  Sharks  are  very  abundant  in  some  beds,  such 
as  the  Upper  Greensand,  and  are  beautifully  preserved.  The 
teeth  of  some  forms  (Carcharias,  &c.)  attain  occasionally  a 
length  of  thr  >e  or  four  inches,  and  indicate  the  existence  in  the 
Cretaceous  seas  of  huge  predaceous  fishes,  probably  larger  than 
any  existing  Sharks.  The  remains  of  Cestracionts  consist 
partly  of  the  flattened  teeth  of  genera  such  as  Acrodus  and 
Ptychodus  (the  latter  confined  to  rocks  of  this  age),  and  partly 
of  the  pointed  teeth  of  Hybodus,  a  genus  which  dates  from  the 
Trias.  In  this  genus  the  teeth  (fig.  206)  consist  of  a  principal 


284  HISTORICAL  PALAEONTOLOGY. 

central  cone,  flanked  by  minor  lateral  cones;  and  the  fin- 
spines  (fig.  207)  are  longitudinally  grooved,  and  carry  a  series 
of  small  spines  on  their  hinder  or  concave  margin.  Lastly, 
the  great  modern  order  of  the  Bony  Fishes  or  Teleosteans 


Fig.  206.— Tooth 
of  Hybodus. 


Fig.  207.— Fin-spine  of  Hybodus.    Lower  Greensand. 


makes  its  first  appearance  in  the  Upper  Cretaceous  rocks, 
where  it  is  represented  by  forms  belonging  to  no  less  than 
three  existing  groups — namely,  the  Salmon  family  (Sal- 
monidce),  the  Herring  family  (Clupeidce},  and  the  Perch  family 
(Percida).  All  these  fishes  have  thin,  horny,  overlapping 
scales,  symmetrical  ("  homocercal ")  tails,  and  bony  skeletons. 


Fig.  208.— 1,  Beryx  Lewesiensts,  a  Percoid  fish  from  the  Chalk  ;  2,  Osmeroides 
Mantelli,  a  Salmonoid  fish  from  the  Chalk. 

The  genus  Beryx    (fig.   208,    i)    is  one  represented  by   existing 
species   at   the  present  day,   and  belongs  to  the   Perch   family. 


THE  CRETACEOUS  PERIOD.  285 

The  genus  Osmeroides,  again  (fig.  208,  2),  is  supposed  to  be 
related  to  the  living  Smelts  (Osmerus),  and,  therefore,  to 
belong  to  the  Salmon  tribe. 

No  remains  of  Amphibians  have  hitherto  been  detected  in 
any  part  of  the  Cretaceous  series;  but  Reptiles  are  extremely 
numerous,  and  belong  to  very  varied  types.  As  regards  the 
great  extinct  groups  of  Reptiles  which  characterize  the  Meso- 
zoic  period  as  a  whole,  the  huge  "  Enaliosaurs "  or  "  Sea- 
Lizards  "  are  still  represented  by  the  Ichthyosaur  and  the 
Plesiosaur.  Nearly  allied  to  the  latter  of  these  is  the  Elas- 
mosaurus  of  the  American  Cretaceous,  which  combined  the 
long  tail  of  the  Ichthyosaur  with  the  long  neck  of  the  Plesio- 
saur. The  length  of  this  monstrous  Reptile  could  not  have 
been  less  than  fifty  feet,  the  neck  consisting  of  over  sixty 
vertebrae  and  measuring  over  twenty  feet  in  length.  The 
extraordinary  Flying  Reptiles  of  the  Jurassic  are  likewise  well 
represented  in  the  Cretaceous  rocks  by  species  of  the  genus 
Pterodactylus  itself,  and  these  later  forms  are  much  more 
gigantic  in  their  dimensions  than  their  predecessors.  Thus 
some  of  the  Cretaceous  Pterosaurs  seem  to  have  had  a  spread 
of  wing  of  from  twenty  to  forty-five  feet,  more  than  realizing 
the  "  Dragons "  of  fable  in  point  of  size.  The  most  remark- 
able, however,  of  the  Cretaceous  Pterosaurs  are  the  forms 
which  have  recently  been  described  by  Professor  Marsh  under 
the  generic  title  of  Pteranodon.  In  these  singular  forms — so 
far  only  known  as  American — the  animal  possessed  a  skeleton 
in  all  respects  similar  to  that  of  the  typical  Pterodactyles, 
except  that  the  jaws  are  completely  destitute  of  teeth.  There 
is,  therefore,  the  strongest  probability  that  the  jaws  were 
encased  in  a  horny  sheath,  thus  coming  to  resemble  the  beak 
of  a  Bird.  Some  of  the  recognized  species  of  Pteranodon  are 
very  small ;  but  the  skull  of  one  species  (P.  longiceps}  is  not 
less  than  a  yard  in  length,  and  there  are  portions  of  the  skull 
of  another  species  which  would  indicate  a  length  of  four  feet 
for  the  cranium.  These  measurements  would  point  to  dimen- 
sions larger  than  those  of  any  other  known  Pterosaurs. 

The  great  Mesozoic  order  of  the  Deinosaurs  is  largely  rep- 
resented in  the  Cretaceous  rocks,  partly  by  genera  which 
previously  existed  in  the  Jurassic  period,  and  partly  by  entirely 
new  types.  The  great  delta-deposit  of  the  Wealden,  in  the 
Old  World,  has  yielded  the  remains  of  various  of  these  huge 
terrestrial  Reptiles,  and  very  many  others  have  been  found  in 
the  Cretaceous  deposits  of  North  America.  One  of  the  most 


286  HISTORICAL  PALEONTOLOGY. 

celebrated  of  the  Cretaceous  Deinosaurs  is  the  Iguanodon,  so 
called  from  the  curious  resemblance  of  its  teeth  to  those  of  the 
existing  but  comparatively  diminutive  Iguana.  The  teeth  (fig. 
209)  are  soldered  to  the  inner  face  of  the  jaw,  instead  of  being 
sunk  in  distinct  sockets ;  and  they  have  the  form  of  somewhat 
flattened  prisms,  longitudinally  ridged  on  the  outer  surface, 
with  an  obtusely  triangular  crown,  and  having  the  enamel 
crenated  on  one  or  both  sides.  They  present  the  extraordinary 
feature  that  the  crowns  became  worn  down  flat  by  mastication, 
showing  that  the  Iguanodon  employed  its  teeth  in  actually 
chewing  and  triturating  the  vegetable  matter  on  which  it  fed. 
There  can  therefore  be  no  doubt  but  that  the  Iguanodon,  in 
spite  of  its  immense  bulk,  was  an  herbivorous  Reptile,  and 
lived  principally  on  the  foliage  of  the  Cretaceous  forests 
amongst  which  it  dwelt.  Its  size  has  been  variously  estimated 
at  from  thirty  to  fifty  feet,  the  thigh-bone  in  large  examples 


Fig.  209.— Teeth  of  Iguanodon  Mantellii.    Wealden,  Britain. 


measuring  nearly  five  feet  in  length,  with  a  circumference  of 
twenty-two  inches  in  its  smallest  part.  With  the  strong  and 
massive  hind-limbs  are  associated  comparatively  weak  and 
small  fore-limbs;  and  there  seems  little  reason  to  doubt  that 
the  Iguanodon  must  have  walked  temporarily  or  permanently 


THE  CRETACEOUS  PERIOD.  287 

upon  its  hind-limbs,  after  the  manner  of  a  Bird.  This  conjec- 
ture is  further  supported  by  the  occurrence  in  the  strata  which 
contain  the  bones  of  the  Iguanodon  of  gigantic  three-toed  foot- 
prints, disposed  singly  in  a  double  track.  These  prints  have 
undoubtedly  been  produced  by  some  animal  walking  on  two 
legs;  and  they  can  hardly,  with  any  probability,  be  ascribed  to 
any  other  than  this  enormous  Reptile.  Closely  allied  to  the 


Fig.  210.— Skull  of  Mosasaurua  Camperi,  greatly  reduced.    Maestrlcht  Chalk. 


Iguanodon  is  the  Hadrosaurus  of  the  American  Cretaceous,  the 
length  of  which  is  estimated  at  twenty-eight  feet.  Iguanodon 
does  not  appear  to  have  possessed  any  integumentary  skeleton ; 
but  the  great  Hyl&osaurus  of  the  Wealden  seems  to  have  been 
furnished  with  a  longitudinal  crest  of  large  spines  running 
down  the  back,  similar  to  that  which  is  found  in  the  compara- 
tively small  Iguanas  of  the  present  day.  The  Megalosaurus  of 
the  Oolites  continued  to  exist  in  the  Cretaceous  period;  and,  as 
we  have  previously  seen,  it  was  carnivorous  in  its  habits.  The 
American  Lalaps  was  also  carnivorous,  and,  like  the  Megalosaur, 
which  it  very  closely  resembles,  appears  to  have  walked  upon 
its  hind-legs,  the  fore-limbs  being  disproportionately  small. 

Another  remarkable  group  of  Reptiles,  exclusively  confined 
to  the  Cretaceous  series,  is  that  of  the  Mosasauroids,  so  called 


288  HISTORICAL  PALEONTOLOGY. 

from  the  type-genus  Mosasaurus.  The  first  species  of  Mosa- 
saurus known  to  science  was  the  M.  Camperi  (fig.  210),  the 
skull  of  which — six  feet  in  length — was  discovered  in  1780  in 
the  Maestricht  Chalk  at  Maestricht.  As  this  town  stands  on 
the  river  Meuse,  the  name  of  Mosasaurus  ("  Lizard  of  the 
Meuse")  was  applied  to  this  immense  Reptile.  Of  late  years 
the  remains  of  a  large  number  of  Reptiles  more  or  less  closely 
related  to  Mosasaurus,  or  absolutely  belonging  to  it  have  been 
discovered  in  the  Cretaceous  deposits  of  North  America,  and 
have  been  described  by  Professors  Cope  ami  Marsh.  All 
the  known  forms  of  this  group  appear  to  have  been  of  large 
size — one  of  them,  Mosasaurus  prince ps,  attaining  the  length  of 
seventy-five  or  eighty  feet,  and  thus  rivalling  the  largest  of  ex- 
isting Whales  in  its  dimensions.  The  teeth  in  the  "  Mosa- 
sauroids "  are  long,  pointed,  and  slightly  curved;  and  instead 
of  being  sunk  in  distinct  sockets,  they  are  firmly  amalgamated 
with  the  jaws,  as  in  modern  Lizards.  The  palate  also  carried 
teeth,  and  the  lower  jaw  was  so  constructed  as  to  allow  of  the 
mouth  being  opened*  to  an  immense  width,  somewhat  as  in  the 
living  Serpents.  The  body  was  long  and  snake-like,  with  a 
very  long  tail,  which  is  laterally  compressed,  and  must  have 
served  as  a  powerful  swimming-apparatus.  In  addition  to  this, 
both  pairs  of  limbs  have  the  bones  connecting  them  with  the 
trunk  greatly  shortened;  whilst  the  digits  were  enclosed  in  the 
integuments,  and  constituted  paddles,  closely  resembling  (in 
structure  the  "  flippers "  of  Whales  and  Dolphins.  The  neck 
is  sometimes  moderately  long,  but  oftener  very  short,  as  the 
great  size  and  weight  of  the  head  would  have  led  one  to  antic- 
ipate. Bony  plates  seem  in  some  species  to  have  formed  an 
at  any  rate  partial  covering  to  the  skin;  but  it  is  not  certain 
that  these  integumentary  appendages  were  present  in  all.  Up- 
on the  whole,  there  can  be  no  doubt  but  that  the  Mosasauroid 
Reptiles — the  true  "  Sea-serpents "  of  the  Cretaceous  period — 
were  essentially  aquatic  in  their  habits,  frequenting  the  sea, 
and  only  occasionally  coming  to  the  land. 

The  "  Mosasauroids "  have  ger.crr'.ly  been  regarded  as  a 
greatly  modified  group  of  the  Lizards  (Lacertilia').  Whether 
this  reference  be  correct  or  not — and  recent  investigations 
render  it  dubious — the  Cretaceous  rocks  have  yielded  the 
remains  of  small  Lizards  not  widely  removed  from  existing 


THE  CRETACEOUS  PERIOD. 


forms.     The  recent  order  of  the  Chelonians  is  also  represented 

in  the  Cretaceous  rocks, 
by  forms  closely  re- 
sembling living  types. 
Thus  the  fresh-water 
deposits  of  the  Wealden 
have  yielded  examples 
of  the  "  Terrapins  "  or 
"Mud-Turtles"  (Emys)  ; 
and  the  marine  Creta- 
ceous strata  have  been 
found  to  contain  the 
remains  of  various  spe- 
cies of  Turtles,  one  of 
which  is  here  figured 
(fig.  211 ).  No  true 
Serpents  (Ophidia)  have 
as  yet  been  detected  in 
the  Cretaceous  -rocks; 
and  this  order  does  not 
appear  to  have  come 
into  existence  till  the 
Tertiary  period.  Last- 
ly, true  Crocodiles  are 
known  to  have  existed 
in  considerable  num- 
bers in  the  Cretaceous  period.  The  oldest  of  these  occur 
in  the  fresh-water  deposits  of  the  Wealden ;  and  they  differ  from 
the  existing  forms  of  the  group  in  the  fact  that  the  bodies 
of  the  vertebrae,  like  those  of  the  Jurassic  Crocodiles,  are 
bi-concave,  or  hollowed  out  at  both  ends.  In  the  Greensand 
of  North  America,  however,  occur  the  remains  of  Crocodiles 
which  agree  with  all  the  living  species  in  having  the  bodies  of 
the  vertebrae  in  the  region  of  the  back  hollowed  out  in  front 
and  convex  behind. 

Birds  have  not  hitherto  been  shown,  with  certainty,  to  have 
existed  in  Europe  during  the  Cretaceous  period,  except  in  a 
few  instances  in  which  fragmentary  remains  belonging  to  this 
class  have  been  discovered.  The  Cretaceous  deposits  of 
North  America  have,  however,  been  shown  by  Professor 
Marsh  to  contain  a  considerable  number  of  the  remains  of 
Birds,  often  in  a  state  of  excellent  preservation.  Some  of 
these  belong  to  swimming  or  Wading  Birds,  differing  in  no 
19 


Fig.  211.— Carapace  of  Chelone  Benatedi. 
Lower  Chalk .    ( After  Owen . ) 


2QO  HISTORICAL  PALEONTOLOGY. 

point  of  special  interest  from  modern  birds  of  similar  habits. 
Others,  however,  exhibit  such  extraordinary  peculiarities  that 
they  merit  more  than  a  passing  notice.  One  of  the  forms  in 
question  constitutes  the  genus  Ichthyornis  of  Marsh,  the  type 
species  of  which  (7.  disbar}  was  about  as  large  as  a  Pigeon. 
In  two  remarkable  respects,  this  singular  Bird  differs  from  all 
known  living  members  of  the  class.  One  of  these  respects 
concerns  the  jaws,  both  of  which  exhibit  the  Reptilian  char- 
acter of  being  armed  with  numerous  small  pointed  teeth  (fig. 
212,  a),  sunk  in  distinct  sockets.  No  existing  bird  possesses 
teeth;  and  this  character  forcibly  recalls  the  Bird-like  Ptero- 
saurs, with  their  toothed  jaws.  Ichthyornis,  however,  possessed 
fore-limbs  constructed  strictly  on  the  type  of  the  "  wing  "  of  the 
living  Birds;  and  it  cannot,  therefore,  be  separated  from  this 
class.  Another  extraordinary  peculiarity  of  Ichthyornis  is,  that 
the  bodies  of  the  vertebra  (fig.  213,  c}  were  bi-concave,  as  is  the 
case  with  many  extinct  Reptiles  and  almost  all  Fishes,  but  as 
does  not  occur  in  any  living  Bird.  There  can  be  little  doubt 
that  Iththyornis  was  aquatic  in  its  habits,  and  that  it  lived  prin- 
cipally upon  fishes ;  but  its  powerful  wings  at  the  same  time 
indicate  that  it  was  capable  of  prolonged  flight.  The  tail  of 
Ichthyornis  has,  unfortunately,  not  been  discovered;  and  it  is 
at  present  impossible  to  say  whether  this  resembled  the  tail  of 
existing  Birds,  or  whether  it  was  elongated  and  composed  of 
separate  vertebrae,  as  in  the  Jurassic  Arcliceopteryx. 

Still  more  wonderful  than  Ichthyornis  is  the  marvellous  bird 
described  by  Marsh  under  the  name  of  Hesperornis  regalis. 
This,  presents  us  with  a  gigantic  diving  bird,  somewhat  re- 
sembling the  existing  "Loons"  (Colymbus},  but  agreeing 
with  Ichthyornis  in  having  the  jaws  furnished  with  conical, 
recurved,  pointed  teeth  (fig.  212,  fr).  Hence  these  forms  are 
grouped  together  in  a  new  sub-class,  under  the  name  of  Odon- 
'tornithes  or  "Toothed  Birds."  The  teeth  of  Hesperornis  (fig. 
212,  d~)  resemble  those  of  Ichthyornis  in  their  general  form; 
but  instead  of  being  sunk  in  distant  sockets,  they  are  simply 
implanted  in  a  deep  continuous  groove  in  the  bony  substance 
of  the  jaw.  The  front  of  the  upper  jaw  does  not  carry  teeth, 
and  was  probably  encased  in  a  horny  beak.  The  breast-bone 
is  entirely  destitute  of  a  central  ridge  or  keel,  and  the  wings 
are  minute  and  quite  rudimentary;  so  that  Hesperornis,  unlike 
Ichthyornis,  must  have  been  wholly  deprived  of  the  power  of 
flight,  in  this  respect  approaching  the  existing  Penguins.  The 
tail  consists  of  about  twelve  vertebrae,  of  which  the  last  three  or 


THE  CRETACEOUS  PERIOD. 


291 


four  are  amalgamated  to  form  a  flat  terminal  mass,  there  being 
at  the  same  time  clear  indications  that  the  tail  was  capable 
of  up  and  down  movement  in  a  vertical  plane,  this  prob- 
ably fitting  it  to  serve  as  a  swimming-paddle  or  rudder.  The 
legs  were  powerfully  constructed,  and  the  feet  were  adapted  to 
assist  the  bird  in  rapid  motion  through  the  water.  The  known 
remains  of  Hesperornis  regalis  prove  it  to  have  been  a  swim- 
ming and  diving  bird,  of  larger  dimensions  than  any  of  the 
aquatic  members  of  the  class  of  Birds  with  which  we  are  ac- 
quainted at  the  present  day.  It  appears  to  have  stood  between 
five  and  six  feet  high,  and  its  inability  to  fly  is  fully  compen- 
sated for  by  the  numerous  adaptations  of  its  structure  to  a 


Fig.  212.— Toothed  Birds  (Odontornithes}  of  the  Cretaceous  Rocks  of  America,  a, 
Left  lower  jaw  of  Ichlhyornis  dispar,  slisrhtly  enlarged  ;  ft,  Left  lower  jaw  of  Hesperor- 
nia  regalis,  reduced  to  nearly  one-fourth  of  the  natural  size  ;  c.  Cervical  vertebra  of 
Ir/itiii/ornis  dispar,  front  view,  twice  the  natural  size  ;  c'.  Side  view  of  the  same  ;  d, 
Tooth  of  Hesperornis  regalia,  enlarged  to  twice  the  natural  size.  (After  Marsh.) 


watery  life.  Its  teeth  prove  it  to  have  been  carnivorous  in  its 
habits,  and  it  probably  lived  upon  fishes.  It  is  a  curious  fact 
that  two  Birds  agreeing  with  one  another  in  the  wholly  abnor- 
mal character  of  possessing  teeth,  and  in  other  respects  so 
entirely  different,  should,  like  IchtJiyornis  and  Hesperornis, 
have  lived  not  only  in  the  some  geological  period,  but  also  in 
the  same  geographical  area;  and  it  is  equally  curious  that 
the  area  inhabited  by  these  toothed  Birds  should  at  the  same 


2Q2  HISTORICAL  PALEONTOLOGY. 

time  have  been  tenanted  by  winged  and  bird-like  Reptiles 
belonging  to  the  toothed  genus  Pterodactylus  and  the  toothless 
genus  Pteranodon. 

No  remains  of  Mammals,  finally,  have  as  yet  been  detected 
in  any  sedimentary  accumulation  of  Cretaceous  age. 


LITERATURE. 


The  following  list  comprises  of  the  more  important  works  and 
memoirs  which  may  be  consulted  with  reference  to  the  Creta- 
ceous strata  and  their  fossil  contents  : — 

1 i )  '  Memoirs  of  the  Geological  Survey  of  Great  Britain. ' 

(2)  '  Geology  of  England  and  Wales. '  Conybeare  and  Phil- 

lips. 

(3)  'Geology  of  Yorkshire,'  vol.  ii.     Phillips. 

(4)  'Geology  of  Oxford  and  the  Thames  Valley.'     Phillips. 

(5)  'Geological  Excursions  through  the  Isle  of  Wight.'  Man- 

tell. 

(6)  '  Geology  of  Sussex. '     Mantell. 

(7)  '  Report  on  Londonderry, '  &c.     Portlock. 

(8)  '  Recherches  sur  le  Terrain  Cretace  Superieur  de   1'Ang- 
leterre  et  de  1'Irlande. '     Barrois. 

(9)  "Geological   Survey  of  Canada" — 'Report  of   Progress, 

1872-73. ' 

(10)  'Geological  Survey  of  California.'    Whitney. 

(n)  'Geological   Survey  of   Montana,   Idaho,  Wyoming,   and 
Utah. '    Hayden  and  Meek. 

(12)  'Report    on     Geology,'    &c.     (British     North     America 

Boundary  Commission).  G.  M.  Dawson. 

(13)  'Manual  of  Geology.'    Dana. 

(14)  'Lethaea  Rossica. '  Eichwald. 

(15)  '  Petrefacta  Germanise. '    Goldfuss. 

(16)  'Fossils  of  the  South  Downs.'     Mantell. 

(17)  'Medals  of  Creation.'     Mantell. 

(18)  '  Mineral  Conchology. '     Sowerby. 

(19)  'Lethaea  Geognostica. '     Bronn. 

(20)  '  Malacostracous    Crustacea    of    the    British    Cretaceous 

Formation'   ( Paheontographical  Society).     Bell. 

(21)  '  Brachiopoda    of    the    Cretaceous    Formation'    Palseon- 

tographical  Society).     Davidson. 

(22)  'Corals  of  the  Cretaceous  Formation'   ( Palaeontograph- 
ical  Society).    Milne-Edwards  and  Haime. 


THE  CRETACEOUS  PERIOD.  293 

(23)  *  Supplement   to   the   Fossil    Corals'    (Palaeontographical 

Society).     Martin  Duncan. 

(24)  '  Echinodermata  of  the  Cretaceous  Formation'   (Palaeon- 

tographical  Society).     Wright. 

(25)  'Monograph    of    the    Belemnitidae '     (Pakeontographical 

Society).     Phillips. 

(26)  'Monograph   of   the   Trigoniae'    (Palaeontographical    So- 
ciety).    Lycett. 

(27)  'Fossil  Cirripedes '  (Palaeontographical  Society).  Darwin. 

(28)  'Fossil   Mollusca  of  the  Chalk  of   Britain'    (Palaeonto- 
graphical Society).    Sharpe. 

(29)  '  Entomostraca  of  the  Cretaceous  Formation'    (Palaeon- 

tographical Society).    Rupert  Jones. 

(30)  '  Monograph   of   the   Fossil   Reptiles   of   the    Cretaceous 

Formation'   (Palaeontographical  Society).     Owen. 

(31)  'Manual  of  Palaeontology.'    Owen. 

(32)  '  Synopsis  of  Extinct  Batrachia  and  Reptilia. '  Cope. 
(33}  "  Structure    of    the    Skull    and    Limbs    in    Mosasauroid 

Reptiles  " — '  American  Journ.  Sci.  and  Arts,  1872.'  Marsh. 

(34)  "  On  Odontornithes  " — '  American  Journ.   Sci.  and  Arts, 

1875. '    Marsh. 

(35)  *  Ossemens  Fossiles. '     Cuvier. 

(36)  '  Catalogue  of  Ornithosauria. '    Seeley. 

(37)  '  Paleontologie  Frangaise. '     D'Orbigny. 

(38)  '  Synopsis  des  Echinides  fossiles. '    Desor. 

(39)  '  Cat.  Raisonne  des  Echinides. '    Agassiz  and  Desor. 

(40)  "  Echinoids  " — '  Decades  of  the  Geol.  Survey  of  Britain. ' 

E.  Forbes. 

(41)  'Paleontologie  Franchise. '    Cotteau. 

(42)  '  Versteinerungen     der     Bohmischen     Kreide-formation. ' 

Reuss. 

(43)"  Cephalopoda,  Gasteropoda,  Pelecypoda,  Brachiopoda, 
&c.,  of  the  Cretaceous  Rocks  of  India " — '  Palaeonto- 
logica  Indica, '  ser.  i.,  iii.,  v.,  vi.,  viii.  Stoliczka. 

(44)  "  Cretaceous    Reptiles    of   the   United    States "— '  Smith- 

sonian Contributions  to  Knowledge,'  vol.  xiv.    Leidy. 

(45)  '  Invertebrate    Cretaceous,    and    Tertiary    Fossils   of    the 

Upper  Missouri  Country. '  1876.    Meek. 


294  HISTORICAL  PALAEONTOLOGY. 

/ 

CHAPTER  XVIII. 
THE  EOCENE  PERIOD. 

Before  commencing  the  study  of  the  subdivisions  of  the 
Kainozoic  series,  there  are  some  general  considerations  to  be 
noted.  In  the  first  place,  there  is  in  the  Old  World  a  com- 
plete and  entire  physical  break  between  the  rocks  of  the 
Mesozoic  and  Kainozoic  periods.  In  no  instance  in  Europe 
are  Tertiary  strata  to  be  found  resting  conformably  upon  any 
Secondary  rock.  The  Chalk  has  invariably  suffered  much 
erosion  and  denudation  before  the  lowest  Tertiary  strata  were 
deposited  upon  it.  This  is  shown  by  the  fact  that  the  actually^ 
eroded  surface  of  the  Chalk  can  often  be  seen;  or,  failing  this, 
that  we  can  point  to  the  presence  of  the  chalk-flints  in  the 
Tertiary  strata.  This  last,  of  course,  affords  unquestionable 
proof  that  the  Chalk  must  have  been  subjected  to  enormous 
denudation  prior  to  the  formation  of  the  Tertiary  beds,  all  the 
chalk  itself  having  been  removed,  and  nothing  left  but  the 
flints,  while  these  are  all  rolled  and  rounded.  In  the  continent 
of  North  America,  on  the  other  hand,  the  lowest  Tertiary  strata 
have  been  shown  to  graduate  downwards  conformably  with  the 
highest  Cretaceous  beds,  it  being  a  matter  of  difficulty  to  draw 
a  precise  line  of  demarcation  between  the  two  formations. 

In  the  second  place,  there  is  a  marked  break  in  the  life  of 
the  Mesozoic  and  Kainozoic  periods.  With  the  exception  of 
a  few  Foraminifera,  and  one  Brachiopod  (the  latter  doubtful), 
no  Cretaceous  species  is  known  to  have  survived  the  Creta- 
ceous period;  while  several  characteristic  families,  such  as  the 
Ammonitida ',  Belemnitida,  and  Hippuritida,  died  out  entirely 
with  the  close  of  the  Cretaceous  rocks.  In  the  Tertiary  rocks, 
on  the  other  hand,  not  only  are  all  the  animals  and  plants 
more  or  less  like  existing  types,  but  we  meet  with  a  constantly- 
increasing  number  of  living  species  as  we  pass  from  the  bottom 
of  the  Kainozoic  series  to  the  top.  Upon  this  last  fact  is 
founded  the  modern  classification  of  the  Kainozoic  rocks, 
propounded  by  Sir  Charles  Lyell. 

The  absence  in  strata  of  Tertiary  age  of  the  chambered 
Cephalopods,  the  Belemnites,  the  Hippurites,  the  Inocerami, 
and  the  diversified  types  of  Reptiles  which  form  such  con- 


THE  EOCENE  PERIOD.  295 

spicuous  features  in  the  Cretaceous  fauna,  render  the  palseon- 
tological  break  between  the  Chalk  and  the  Eocene  one  far  too 
serious  to  be  overlooked.  At  the  same  time,  it  is  to  be  re- 
membered that  the  evidence  afforded  by  the  explorations  car- 
ried out  of  late  years  as  to  the  animal  life  of  the  deep  sea,  ren- 
ders it  certain  that  the  extinction  of  marine  forms  of  life  at  the 
close  of  the  Cretaceous  period  was  far  less  extensive  than  had 
been  previously  assumed.  It  is  tolerably  certain,  in  fact,  that 
we  may  look  upon  some  of  the  inhabitants  of  the  depths  of  our 
existing  oceans  as  the  direct,  if  modified,  descendants  of  ani-* 
mals  which  were  in  existence  when  the  Chalk  was  deposited. 

It  follows  from  the  general  want  of  conformity  between  the 
Cretaceous  and  Tertiary  rocks,  and  still  more  from  the  great 
difference  in  life,  that  the  Cretaceous  and  Tertiary  periods  are 
separated,  in  the  Old  World  at  any  rate,  by  an  enormous  lapse 
of  unrepresented  time.  How  long  this  interval  may  have  been, 
we  have  no  means  of  judging  exactly,  but  it  very  possibly  was 
as  long  as  the  whole  Kainozoic  epoch  itself.  Some  day  we 
shall  doubtless  find,  at  some  part  of  the  earth's  surface,  marine 
strata  which  were  deposited  during  this  period,  and  which  will 
contain  fossils  intermediate  in  character  between  the  organic 
remains  which  respectively  characterize  the  Secondary  and 
Tertiary  periods.  At  present,  we  have  only  slight  traces  of 
such  deposits — as,  for  instance,  the  Maestricht  beds,  the  Faxoe 
Limestone,  and  the  Pisolitic  Limestone  of  France. 

CLASSIFICATION  OF  THE  TERTIARY  ROCKS. — The  classifica- 
tion of  the  Tertiary  rocks  is  a  matter  of  unusual  difficulty,  in 
consequence  of  their  occurring  in  disconnected  basins,  form- 
ing a  series  of  detached  areas,  which  hold  no  relations  of 
superposition  to  one  another.  The  order,  therefore,  of  the 
Tertiaries  in  point  of  time,  can  only  be  determined  by  an  ap- 
peal to  fossils;  and  in  such  determination  Sir  Charles  Lyell 
proposed  to  take  as  the  basis  of  classification  the  proportion  of 
living  or  existing  species  of  Mollusca  which  occurs  in  each  stra- 
tum or  group  of  strata.  Acting  upon  this  principle,  Sir  Charles 
Lyell  divides  the  Tertiary  series  into  four  groups : — 

I.  The  Eocene  formation  (Gr.  eos,  dawn;  kainos,  new),  con- 
taining the  smallest  proportion  of  existing  species,  and  being, 
therefore,  the  oldest  division.  In  this  classification,  only  the 
Mollusca  are  taken  into  account;  and  it  was  found  that  of 
these  about  three  and  a  half  per  cent  were  identical  with  ex- 
isting species. 


296  HISTORICAL  PALAEONTOLOGY. 

II.  The  Miocene  formation   (Gr.  melon,  less;  kainos,  new), 
with  more  recent  species  than  the  Eocene,  but  less  than  the  suc- 
ceeding formation,  and  less  than  one-half  the  total  number  in  the 
formation.     As  before,  only  the  Mollusca  are  taken  into  account, 
and  about  17  per  cent  of  these  agree  with  existing  species. 

III.  The  Pliocene  formation  (Gr.  Pleion,  more;  kainos,  new) 
with  generally  more  than  half  the  species  of  shells  identical  with 
existing    species — the   proportion    of    these   varying    frora  35    to 
50  per  cent  in  the  lower  beds  of  this  division,  up  to  90  or  95 
per  cent  in  its  higher  portion. 

IV.  The  Post-Tertiary  Formations,  in  which  all  the  shells 
belong   to   existing  species.     This,   in   turn,   is   divided  into   two 
minor    groups — the   Post-Pliocene   and   Recent   Formations.      In 
the  Post-PUncene  formations,  while  all  the  Mollusca  belong  to 
existing    species,    most    of    the    Mammals    belong    to    extinct 
species.     In  the  Recent  period,  the  quadrupeds,  as  well   as  the 
shells,  belong  to  living  species. 

The  above,  with  some  modifications,  was  the  original  classi- 
fication proposed  by  Sir  Charles  Lyell  for  the  Tertiary  rocks, 
and  now  universally  accepted.  More  recent  researches,  it  is 
true,  have  somewhat  altered  the  proportions  of  existing  species 
to  extinct,  as  stated  above.  The  general  principle,  however, 
of  an  increase  in  the  number  of  living  species,  still  holds  good  ; 
and  this  is  as  yet  the  only  satisfactory  basis  upon  which  it  has 
been  proposed  to  arrange  the  Tertiary  deposits. 


EOCENE  FORMATION. 


The  Eocene  rocks  are  the  lowest  of  the  Tertiary  series,  and 
comprise  all  those  Tertiary  deposits  in  which  there  is  only  a 
small  proportion  of  existing  Mollusca — from  three  and  a  half 
to  five  per  cent.  The  Eocene  rocks  occur  in  several  basins  in 
Britain,  France,  the  Netherlands,  and  other  parts  of  Europe, 
and  in  the  United  States.  The  subdivisions  which  have  been 
established  are  extremely  numerous,  and  it  is  often  impossible 
to  parallel  those  of  one  basin  with  those  of  another.  It  will 
be  sufficient,  therefore,  to  accept  the  division  of'  the  Eocene 
formation  into  three  great  groups — Lower,  Middle,  and  Upper 


THE  EOCENE  PERIOD.  297 

Eocene — and    to    consider    some    of    the    more    important    beds 
comprised  under  these  heads  in  Europe  and  in  North  America. 

I.  EOCENE    OF     BRITAIN.       (i.)   LOWER    EOCENE. — The    base 
of  the  Eocene  series  in   Britain  is  constituted  by  about  90  feet 
of  light-colored,  sometimes  argillaceous  sands    (Thanet  Sands), 
which  are  of  marine  origin.     Above  these,  or  forming  the  base 
of  the  formation  where  these  are  wanting,  come  mottled  clays 
and  sands  with  lignite    (Woolwich  and  Reading  series'),  which 
are  estuarine  or  fluvio-marine  in  origin.     The  highest  member 
of  the  Lower  Eocene  of  Britain  is  the  "  London  Clay, "  consist- 
ing of  a  great  mass  of  dark-brown  or  blue  clay,  sometimes  with 
sandy  beds,  or  with  layers  of  "  septaria, "  the  whole  attaining  a 
thickness   of    from   200  to   as   much   as   500   feet.     The   London 
Clay  is  a  purely  marine  deposit,  containing  many  marine  fossils, 
with  the  remains  of  terrestrial  animals  and  plants;  all  of  which 
indicate    a    high    temperature    of    the    sea    and   tropical    or    sub- 
tropical condition  of  the  land. 

(2.)  MIDDLE  EOCENE. — The  inferior  portion  of  the  Middle 
Eocene  of  Britain  consists  of  marine  beds,  chiefly  consisting 
of  sand,  clays,  and  gravels,  and  attaining  a  very  considerable 
thickness  (Bagshot  and  Bracklesham  beds).  The  superior  por- 
tion of  the  Middle  Eocene  of  Britain,  on  the  other  hand,  con- 
sists of  deposits  which  are  almost  exclusively  fresh-water  or 
brackish-water  in  origin  (Headon  and  Osborne  series). 

The  chief  Continental  formations  of  Middle  Eocene  age  are 
the  "  Calcaire  grossier "  of  the  Paris  basin,  and  the  "  Num- 
mulitic  Limestone"  of  the  Alps. 

(3.)  UPPER  EOCENE. — If  the  Headon  and  Osborne  beds  of 
the  Isle  of  Wight  be  placed  in  the  Middle  Eocene,  the  only 
British  representatives  of  the  upper  Eocene  are  the  Bembridge 
beds.  These  strata  consist  of  limestones,  clays,  and  marls, 
which  have  for  the  most  part  been  deposited  in  fresh  or  brack- 
ish water. 

II.  EOCENE     BEDS     OF     THE     PARIS     BASIN. — The     Eocene 
strata   are   very  well    developed   in   the  neighborhood   of    Paris, 
where   they  occupy  a   large  area  or  basin   scooped  out  of  the 
Chalk.     The  beds  of  this  area  are  partly  marine,  partly   fresh- 
water   in    origin ;    and    the    following    table    (after    Sir    Charles 
Lyell)    shows  their  subdivisions  and  their  parallelism  with  the 
English  series: — 


2o8  HISTORICAL  PALEONTOLOGY. 

GENERAL  TABLE  OF  FRENCH  EOCENE  STRATA. 
UPPER  EOCENE. 

French  Subdivisions.  English  Equivalents. 

A.  i.  Gypseous   series   of  I.  Bembridge  series. 

Montmatre. 
A,  2.  Calcaire  silicieux,  or  2.  Osborne  and  Headon  series. 

Travertin    Inferieur. 

A.  3.  Gres   de    Beauchamp,    or      3.  White  sand  and  clay  of 

Sables  Moyens.  Barton  Cliff,  Hants. 

MIDDLE   EOCENE. 

B.  I.  Calcaire  Grossier.  i.  Bagshot   and   Bracklesham 

B.  2.  Soissonnais    Sands,   or  beds. 

Lits  Coquilliers.  2.  Wanting. 

LOWER   EOCENE. 

C.  i.  Argile  de  Londres  at  i.  London  clay. 

base  of  Hill  of  Cassel, 

near  Dunkirk. 
C.  2.  Argile  plastique  and  lig-      2.  Plastic   clay   and   sand  with 

nite.  lignite     (Woolwich 

and   Reading   series). 
C.  3.  Sables  de  Bracheux.  3.  Thanet  sands. 

III.  EOCENE  STRATA  OF  THE  UNITED  STATES. — The  low- 
est member  of  the  Eocene  deposits  of  North  America^  is  the 
so-called  "  Lignitic  Formation,"  which  is  largely  developed  in 
Mississippi,  Tennessee,  Arkansas,  Wyoming,  Utah,  Colorado, 
and  California,  and  sometimes  attain  a  thickness  of  several 
thousand  feet.  Stratigraphically,  this  formation  exhibits  the 
interesting  point  that  it  graduates  downwards  insensibly  and 
conformably  into  the  Cretaceous,  whilst  it  is  succeeded  uncon- 
formably  by  strata  of  Middle  Eocene  age.  Lithologically,  the 
series  -consists  principally  of  sands  and  clays,  with  beds  of  lig- 
nite and  coal,  and  its  organic  remains  show  that  it  is  principally 
of  fresh-water  origin  with  a  partial  intermixture  of  marine  beds. 
These  marine  strata  of  the  "  Lignitic  formation  ';  are  of  special 
interest,  as  showing  such  a  commingling  of  Cretaceous  and 
Tertiary  types  of  life,  that  it  is  impossible  to  draw  any  rigid 
line  in  this  region  between  the  Mesozoic  and  Kainozoic  sys- 
tems. Thus  the  marine  beds  of  the  Lignitic  series  contain 
such  characteristic  Cretaceous  forms  as  Inoceramus  and  Am- 


THE  EOCENE  PERIOD.  299 

monites,  along  with  a  great  number  of  Univalves  of  a  distinctly 
Tertiary  type  (Cones,  Cowries,  &c.)  Upon  the  whole,  there- 
fore, we  must  regard  this  series  of  deposits  as  affording  a  kind 
of  transition  between  the  Cretaceous  and  the  Eocene,  holding 
in  some  respects  a  position  which  may  be  compared  with  that 
held  by  the  Purbeck  beds  in  Britain  as  regards  the  Jurassic 
and  Cretaceous. 

The  Middle  Eocene  of  the  United  States  is  represented 
by  the  Claiborne  and  Jackson  beds.  The  Claiborne  series  is 
extensively  developed  at  Claiborne,  Alabama,  and  consists  of 
sands,  clays,  lignites,  marls,  and  impure  limestones,  containing 
marine  fossils  along  with  numerous  plant-remains.  The  Jack- 
son series  is  represented  by  lignitic  clays  and  marls  which  occur 
at  Jackson,  Mississippi.  Amongst  the  more  remarkable  fossils 
of  this  series  are  -the  teeth  and  bones  of  Cretaceans  of  the 
genus  Zeuglodon. 

Strata  of  Upper  Eocene  age  occur  in  North  America  at 
Vicksburg,  Mississippi,  and  are  known  as  the  Vicksburg  series. 
They  consist  of  lignites,  clays,  marls,  and  limestones.  Fresh- 
water deposits  of  Eocene  age  are  also  largely  developed  in 
parts  of  the  Rocky  Mountain  region.  The  most  remarkable 
fossils  of  these  beds  are  Mammals,  of  which  a  large  number  of 
species  have  been  already  determined. 


LIFE  OF  THE  EOCENE  PERIOD. 

The  fossils  of  the  Eocene  deposits  are  so  numerous  that 
nothing  more  can  be  attempted  here  than  to  give  a  brief  and 
general  sketch  of  the  life  of  the  period,  special  attention  being 
directed  to  some  of  the  more  prominent  and  interesting  types, 
amongst  which — as  throughout  the  Tertiary  series — the  Mam- 
mals hold  the  first  place.  It  is  not  uncommon,  indeed,  to 
speak  of  the  Tertiary  period  as  a  whole  under  the  name  of  the 
"Age  of  Mammals, "  a  title  at  least  as  well  deserved  as  that  of 
"  Age  of  Reptiles "  applied  to  the  Mesozoic,  or  "  Age  of  Mol- 
luscs "  applied  to  the  Palaeozoic  epoch. 

As  regards  the  plants  of  the  Eocene,  the  chief  point  to  be 
noticed  is,  that  the  conditions  which  had  already  set  in  with 
the  commencement  of  the  Upper  Cretaceous,  are  here  con- 
tinued, and  still  further  enforced.  The  Cycads  of  the  Secondary 
period,  if  they  have  not  totally  disappeared,  are  exceedingly 
rare;  and  the  Conifers,  losing  the  predominance  which  they 


300 


HISTORICAL  PALAEONTOLOGY. 


enjoyed  in  the  Mesozoic,  are  now  relegated  to  a  subordinate 
though  well-defined  place  in  the  terrestrial  vegetation.  The 
great  majority  of  the  Eocene  plants  are  referable  to  the  groups 
of  the  Angiospermous  Exogens  and  the  Monocotyledons ;  and 
the  vegetation  of  the  period,  upon  the  whole,  approximates 
closely  to  that  now  existing  upon  the  earth.  The  plants  of  the 
European  Eocene  are,  however,  in  the  main  most  closely  allied 
to  forms  which  are  now  characteristic  of  tropical  or  sub-tropical 
regions.  Thus,  in  the  London  Clay  are  found  numerous  fruits 
of  Palms  (Nipadites,  fig.  213),  along  with  various  other  plants, 
most  of  which  indicate  a  warm  climate 
as  prevailing  in  the  south  of  England 
at  the  commencement  of  the  Eocene 
period.  In  the  Eocene  strata  of  North 
America  occur  numerous  plants  belong- 
ing to  existing  types — such  as  Palms, 
Conifers,  the  Magnolia,  Cinnamon,  Fig, 
Dog-wood,  Maple,  Hickory,  Poplar, 
Plane,  &c.  Taken  as  a  whole,  the 
Eocene  flora  of  North  America  is  nearly 
related  to  that  of  the  Miocene  strata  of 
Europe,  as  well  as  that  now  existing 
in  the  American  area.  We  may  con- 
clude, therefore,  that  "  the  forests  of 
the  American  Eocene  resembled  those 

of    the    European    Miocene,    and    even    of    modern    America" 
(Dana). 

As  regards  the  animals  of  the  Eocene  period,  the  Protozoans 
are  represented  by  numerous  Foraminifera,  which  reach  here 
their  maximum  of  development,  "both  as  regards  the  size  of 
individuals  and  the  number  of  generic  types.  Many  of  the 
Eocene  Foraminif ers  are  of  small  size ;  but  even  these  not 
uncommonly  form  whole  rock-masses.  Thus,  the  so-called 
"  Miliolite  Limestone "  of  the  Paris  basin,  largely  used  as  a 
building-stone,  is  almost  wholly  composed  of  the  shells  of  a 
small  species  of  Miliola.  The  most  remarkable,  however,  of 
the  many  members  of  this  group  of  animals  which  flourish  in 
Eocene  times,  are  the  "  Nummulites "  (Nummulina),  so  called 
from  their  resemblance  in  shape  to  coins  (Lat.  nummus,  a  coin). 
The  Nummulites  are  amongst  the  largest  of  all  known  Fora- 
minifera, sometimes  attaining  a  size  of  three  inches  in  circum- 
ference; and  their  internal  structure  is  very  complex  (fig.  214). 
Many  species  are  known,  and  they  are  particularly  character- 


Fig.  213.— Nipadites  ellipti- 
cu8,  the  fruit  of  a  fossil  Palm. 
London  Clay,  Isle  of  Sheppey. 


THE  EOCENE  PERIOD. 


301 


istic  of  the  Middle  and  Upper  of  these  periods — their  place 
being  sometimes  taken  by  Orbitoides,  a  form  very  similar  to  the 
Nummulite  in  external  appearance,  but  differing  in  its  internal 
details.  In  the  Middle  Eocene,  the  remains  of  Nummulites 
are  found  in  vast  numbers  in  very  widely-spread  and  easily- 
recognized  formation  known  as  the  "  Nummulitic  Limestone " 
(fig.  10).  According  to  Sir  Charles  Lyell,  "the  Nummulitic 
Limestone  of  the  Swiss  Alps  rises  to  more  than  10,000  feet 
above  the  level  of  the  sea,  and  attains  here  and  in  other  moun- 
tain-chains a  thickness  of  several  thousand  feet.  It  may  be 
said  to  play  a  far  more  conspicuous  part  than  any  other  Tertiary 
group  in  the  solid  framework  of  the  earth's  crust,  whether  in 
Europe,  Asia,  or  Africa.  It  occurs  in  Algeria  and  Morocco, 
and  has  been  traced  from  Egypt,  where  it  was  largely  quarried 
of  old  for  the  building  of  the  Pyramids,  into  Asia  Minor,  and 
across  Persia  by  Bagdad  to  the  mouths  of  the  Indus.  It  has 
been  observed  not  only  in  Cutch,  but  in  the  mountain-ranges 


Fig.  214. — Nummulina  lotvigata.    Middle  Eocene. 

which  separate  Scinde  from  Persia,  and  which  form  the  passes 
leading  to  Cabul ;  and  it  has  been  followed  still  further  east- 
ward into  India,  as  far  as  Eastern  Bengal  and  the  frontiers  of 
China. "  The  shells  of  Nummulites  have  been  found  at  an 
elevation  of  16,500  feet  above  the  level  of  the -sea  in  Western 
Thibet;  and  the  distinguished  and  philosophical  geologist  just 
quoted,  further  remarks,  that  "  when  we  have  once  arrived  at 
the  conviction  that  the  Nummulitic  formation  occupies  a  mid- 
dle and  upper  place  in  the  Eocene  series,  we  are  struck  with 
the  comparatively  modern  date  to  which  some  of  the  greatest 
revolutions  in  the  physical  geography  of  Europe,  Asia,  and 
Northern  Africa  must  be  referred.  All  the  mountain-chains — 
such  as  the  Alps,  Pyrenees,  Carpathians,  and  Himalayas — into 
the  composition  of  whose  central  and  loftiest  parts  the  Num- 
mulitic strata  enter  bodily,  could  have  had  no  existence  till 


302 


HISTORICAL  PALAEONTOLOGY. 


after  the  Middle  Eocene  period.  During  that  period,  the  sea 
prevailed  where  these  chains  now  rise ;  for  Nummulites  and 
their  accompanying  Testacea  were  unquestionably  inhabitants 
of  salt  water.  " 

The  Ccelcnterates  of  the  Eocene  are  represented  principally 
by  Corals,  mostly  of  types  identical  with  or  nearly  allied  to 
those  now  in  existence.  Perhaps  the  most  characteristic  group 
of  these  is  that  of  the  Turbinolidcc,  comprising  a  number  of 
simple  "cup-corals, "  which  probably  lived  in  moderately  deep 
water.  One  of  the  forms  belonging  to  this  family  is  here 
figured  (fig.  215).  Besides  true  Corals,  the  Eocene  deposits 
have  yielded  the  remains  of  the  "  Sea- 
pens  "  (Pennatulida}  and  the  branched 
skeletons  of  the  "  Sea-shrubs  "  (Gorgonida}. 

The  Echinoderms  are  represented  prin- 
cipally by  Sea-urchins,  and  demand  nothing 
more  than  mention.  It  is  to  be  observed, 
however,  that  the  great  group  of  the  Sea- 
lilies  (Crinoids)  is  now  verging  on  extinc- 
tion, and  is  but  very  feebly  represented. 

Amongst  the  Mollusca,  the  Polyzoans 
and  Brachiopods  also  require  no  special  men- 
tion, beyond  the  fact  that  the  latter  are 
greatly  reduced  in  numbers,  and  belong 
principally  to  the  existing  genera  Tere- 
bratula  and  Rhynchonella.  The  Bivalves 
(Lamellibranchs)  and  the  Univalves  (Gas- 
ieropods)  are  exceedingly  numerous,  and 
almost  all  the  principal  existing  genera  are 
now  represented ;  though  less  than  five 
per  cent  of  the  Eocene  species  are  identical 
with  those  now  living.  It  is  difficult  to 
make  any  selection  from  the  many  Bivalves 
which  are  known  in  deposits  of  this  age; 
but  species  of  Cardita,  Crassatella,  Leda, 
Cyrena,  Mactra,  Cardium,  Psammobia,  &c., 
may  be  mentioned  as  very  characteristic. 
The  Cardita  planicosta  here  figured  (fig. 
216)  is  not  only  very  abundant  in  the 
Middle  Eocene,  but  is  very  widely  distrib- 
uted, ranging  from  Europe  to  the  Pacific  coast  of  North 
America.  The  Univalves .  of  the  Eocene  are  extremely  nu- 
merous, and  generally  beautifully  preserved.  The  majority 


Fig.  2l5.—Turbinolia 
aulcata.  viewed  from  one 
side,  and  from  above. 
Eocene. 


THE  EOCENE  PERIOD. 


303 


of  them  belong  to  that  great  section  of  the  Gasteropods  in 
which  the  mouth  of  the  shell  is  notched  or  produced  into 
a  canal  (when  the  shell  is  said  to  be  "  siphonostomatous ") — 
this  section  including  the  carnivorous  and  most  highly-or- 
ganized groups  of  the  class.  Not  only  is  this  the  case,  but 
a  large  number  of  the  Eocene  Univalves  belong  to  types 
which  now  attain  their  maximum  of  development  in  the 
warmer  regions  of  the  globe.  Thus  we  find  numerous  species 


Fig.  216. — Cardita  planicosta.    Middle  Eocene. 

of  Cones  (Conus},  Volutes  (Valuta},  Cowries  (Cyprcea,  fig.  218), 
Olives  and  Rice-shells  (Olivd),  Mitre-shells  (Mltra},  Trumpet- 
shells  (Triton},  Auger-shells  (Terebra),  and  Fig-shells  (Pyrula). 
Along  with  these  are  many  forms  of  Pleurotoma,  Rostellaria, 
Spindle-shells  (Fusus*),  Dog- whelks  (Nassa},  Murices,  and  many 
round-mouthed  ("holostomatous ")  species,  belonging  to  such 


Fig.  217  .—Typhia  tubifer,  a  "  siphonosto- 
matous ' '  Univalve .    Eocene . 


Fig.  218.    Cyprcea 
elegant.    Eocene. 


genera  as   Turritella,  Nerita,  Natica,  Scalaria,  &c.     The  genus 
Cerithium    (fig.   219),   most   of   the   living    forms   of   which   are 


304 


HISTORICAL  PALEONTOLOGY. 


found  in  warm  regions,  inhabiting  fresh  or  brackish  waters, 
undergoes  a  vast  development  in  the  Eocene  period,  where  it 
is  represented  by  an  immense  number  of  specific  forms,  some 
of  which  attain  very  large  dimensions.  In  the  Eocene  strata 
of  the  Paris  basin  alone,  nearly  one  hundred 
and  fifty  species  of  this  genus  have  been 
detected.  The  more  strictly  fresh-water 
deposits  of  the  Eocene  period  have  also 
yielded  numerous  remains  of  Univalves  such 
as  are  now  proper  to  rivers  and  lakes-,  to- 
gether with  the  shells  of  true  Land-snails. 
Amongst  these  may  be  mentioned  numerous 
species  of  Limncea  (fig.  22o),Physa  (fig.  221), 
Melania,  Paludina,  Planorbis,  Helix,  Buli- 
mus,  and  Cyclostoma  (fig.  222). 

With  regard  to  the  Cephalopods,  the  chief 
point  to  be  noticed  is,  that  all  the  beautiful 
and  complex  forms  which  peculiarly  char- 
acterized the  Cretaceous  period  have  here 
disappeared.  We  no  longer  meet  with  a 
single  example  of  the  Turrilite,  the  Baculite, 
the  Hamite,  the  Scaphite,  or  the  Ammonite.  The  only  ex- 
ception to  this  statement  is  the  occurrence  of  one  species 
of  Ammonite  in  the  so-called  "  Lignitic  Formation "  of  North 
America ;  but  the  beds  containing  this  may  possibly  be  rather 
referable  to  the  Cretaceous — and  this  exception  does  not 
affect  the  fact  that  the  Ammonitida,  as  a  family,  had  be- 


Fig.  219.  —  Cerithi- 
um  hexagenum.  Eo- 
cene. 


Fig.  220.— Limncea 
pyramidalis. 


Fig.  Vll.—Physa 
columnaris.    Eocene. 


Fig.  222.— Cyclostoma 
Arnoudii.    Eocene. 


come  extinct  before  the  Eocene  strata  were  deposited.  The 
ancient  genus  Nautilus  still  survives,  the  sole  representative  of 
the  once  mighty  order  of  the  Tetrabranchiate  Cephalopods. 


THE  EOCENE  PERIOD.  305 

In  the  order  of  the  Dibranchiates,  we  have  a  like  phenomenon 
to  observe  in  the  total  extinction  of  the  great  family  of  the 
"  Belemnites. "  No  form  referable  to  this  group  has  hitherto 
been  found  in  any  Tertiary  stratum;  but  the  internal  skeletons 
of  Cuttle-fishes  (such  as  Belosepia}  are  not  unknown. 

Remains  of  Fishes  are  very  abundant  in  strata  of  Eocene 
age,  especially  in  certain  localities.  The  most  famous  depot 
for  the  fossil  fishes  of  this  period  is  the  limestone  of  Monte 
Bolca,  near  Verona,  which  is  interstratified  with  beds  of  vol- 
canic ashes,  the  whole  being  referable  to  the  Middle  Eocene. 
The  fishes  here  seem  to  have  been  suddenly  destroyed  by  a 
volcanic  eruption,  and  are  found  in  vast  numbers.  Agassiz 


Fig.  223.—Rh(nnbug  minimus,  a  small  fossil  Turbot  from  the  Eocene  Tertiary, 
Monte  Boles. 

has  described  over  one  hundred  and  thirty  species  of  Fishes 
from  this  locality,  belonging  to  seventy-seven  genera.  All 
the  species  are  extinct;  but  about  one-half  of  the  genera  are 
represented  by  living  forms.  The  great  majority  of  the 
Eocene  Fishes  belong  to  the  order  of  the  "  Bony  Fishes " 
(Teleostcans},  so  that  in  the  main  the  forms  of  Fishes  charac- 
terizing the  Eocene  are  similar  to  those  which  predominate 
in  existing  seas.  In  addition  to  the  above,  a  few  Ganoids  and 
a  large  number  of  Placoids  are  known  to  occur  in  the  Eocene 
rocks.  Amongst  the  latter  are  found  numerous  teeth  of  true 
Sharks,  such  as  Otodus  (fig.  224)  and  Carcharodon.  The 
pointed  and  serrated  teeth  of  the  latter  sometimes  attain  a 
20 


306 


HISTORICAL  PALEONTOLOGY. 


length  of  over  half  a  foot,  indicating  that  these  predaceous 
fishes  attained  gigantic  dimensions;  and  it  is  interesting  to 
note  that  teeth,  in  external  appearance  very  similar  to  those 
of  the  early  Tertiary  genus  Carcharodon,  have  been  dredged 


Fig.  224.— Tooth  of 

Otodus  obliquus, 

Eocene. 


Fig.  225.— Flattened  dental  plates  of  a  Ray 
(Myliobatia  Edwardaii) .    Eocene. 


from  great  depths  during  the  recent  expedition  of  the  Chal- 
lenger. There  also  occur  not  uncommonly  the  flattened 
teeth  of  Rays  (fig.  225),  consisting  of  flat  bony  pieces  placed 
close  together,  and  forming  "  a  kind  of  mosaic  pavement  on 
both  the  upper  and  lower  jaws."  (Owen). 

In  the1  class  of  the  Reptiles,  the  disappearance  of  the  char- 
acteristic Mesozoic  types  is  as  marked  a  phenomenon  as  the 
introduction  of  new  forms.  The  Ichthyosaurs,  the  Plesio- 
saurs,  the  Pterosaurs,  and  the  Mosasaurs  of  the  Mesozoic, 
find  no  representatives  in  the  Eocene  Tertiary ;  and  the  same 
is  true  of  the  Deinosaurs,  if  we  except  a  few  remains  from  the 
doubtfully-situated  "Lignitic  formation"  of  the  United  States. 
On  the  other  hand,  all  the  modern  orders  of  Reptiles  are 
known  to  have  existed  during  the  Eocene  period.  The 
Chelonians  are  represented  by  true  marine  Turtles,  by  "Ter- 
rapins" (Emydida?},  and  by  "Soft  Tortoises"  (Trionycida). 
The  order  of  the  Snakes  and  Serpents  (Ophidia)  makes  its 
appearance  here  for  the  first  time  under  several  forms — all  of 
which,  however,  are  referable  to  the  non-venomous  group  of 
the  "Constricting  Serpents"  (Boidce}.  The  oldest  of  these 
is  the  Palceophis  toliapicus  of  the  London  Clay  of  Sheppey, 
first  made  known  to  science  by  the  researches  of  Professor 
Owen.  The  nearly-allied  Palcuophis  typh&us  of  the  Eocene 
beds  of  Bracklesham  appears  to  have  been  a  Boa-constrictor- 
like  Snake  of  about  twenty  feet  in  length.  Similar  Python- 
like  Snakes  (Pal&ophis,  Dinophis,  &c.)  have  been  described 
from  the  Eocene  deposits  of  the  United  States.  True  Lizards 


THE  EOCENE  PERIOD.  307 

(Lacertilians)  are  found  in  some  abundance  in  the  Eocene 
deposits, — some  being  small  terrestrial  forms,  like  the  common 
European  lizards  of  the  present  day ;  whilst  others  equal  or 
exceed  the  living  Monitors  in  size.  Lastly,  the  modern  ordei 
of  the  Crocodilia  is  largely  represented  in  Eocene  times,  by 
species  belonging  to  all  the  existing  genera,  together  with 
others  referable  to  extinct  types.  As  pointed  out  by  Owen, 
it  is  an  interesting  fact  that  in  the  Eocene  rocks  of  the  south- 
west of  England,  there  occur  fossil  remains  of  all  the  three 
living  types  of  Crocodilians — namely,  the  Gavials,  the  true 
Crocodiles,  and  the  Alligators  (fig.  226) — though  at  the 
present  day  these  forms  are  all  geographically  restricted  in 
their  range,  and  are  never  associated  together. 

Almost "  all  the  existing  orders  of  Birds,  if  not  all,  are 
represented  in  the  Eocene  deposits  by  remains  often  very 
closely  allied  to  existing  types.  Thus,  amongst  the  Swimming 
Birds  (Natatores)  we  find  examples  of  forms  allied  to  the 
living  Pelicans  and  Mergansers;  amongst  the  Waders  (Gral- 
latores')  we  have  birds  resembling  the  Ibis  (the  Numenius 
gypsorum  of  the  Paris  basin)  ;  amongst  the  Running  Birds 
(Cursores}  we  meet  with  the  great  Gastornis  Parisiensis,  which 
equalled  the  African  Ostrich  in  height,  and  the  still  more 


Fig.  226. — Upper  jaw  fof  Alligator.    Eocene  Tertiary.  Isle  of  Wight. 

gigantic  Dasontis  Londinensis;  remains  of  a  Partridge  rep- 
resent the  Scratching  Birds  (Rasores)  ;  the  American  Eocene 
has  yielded  the  bones  of  one  of  the  Climbing  Birds  (Scan- 
sores),  apparently  referable  to  the  Woodpeckers;  the  Protornis 
Glarisiensis  of  the  Eocene  Schists  of  Claris  is  the  oldest 
known  example  of  the  Perching  Birds  (Insessores}  ;  and  the 


308  HISTORICAL  PALEONTOLOGY. 

Birds  of  Prey  (Raptores}  are  represented  by  Vultures,  Owls, 
and  Hawks.  The  toothed  Birds  of  the  Upper  Cretaceous 
are  no  longer  known  to  exist ;  but  professor  Owen  has 
recently  described  from  the  London  Clay  the  skull  of  a  very 
remarkable  Bird,  in  which  there  is,  at  any  rate,  an  approxi- 
mation to  the  structure  of  Ichthyornis  and  Hesperornis.  The 
bird  in  question  has  been  named  the  Odontopteryx  toliapicus, 
its  generic  title  being  derived  from  the  very  remarkable  char- 
acters of  its  jaws.  In  this  singular  form  (fig.  227)  the  margins 
of  both  jaws  are  furnished  with  tooth-like  denticulations,  which 
differ  from  true  teeth  in  being  actually  portions  of  the  bony 


Fig.  227. — Skull  of  Odontopteryx  toliapicus,  restored.     ( After  Owen. ) 

substance  of  the  jaw  itself,  with  which  they  are  continuous, 
and  which  were  probably  encased  by  extensions  of  the  horny 
sheath  of  the  bill.  These  tooth-like  processes  are  of  two 
sizes,  the  larger  ones  being  comparable  to  canines ;  and  they 
are  all  directed  forwards,  and  have  a  triangular  or  compressed 
conical  form.  From  a  careful  consideration  of  all  the  dis- 
covered remains  of  this  bird,  Professor  Ow-n  concludes  that 
"  Odontopteryx  was  a  warm-blooded  feathered  biped,  with 
wings ;  and  further,  that  it  was  web-footed  and  a  fish-eater, 
and  that  in  the  catching  of  its  slippery  prey  it  was  assisted  by 
this  Pterosauroid  armature  of  its  jaws. "  Upon  the  whole, 
Odontopteryx  would  appear  to  be  most  nearly  related  to  the 
family  of  the  Geese  (Anserince)  or  Ducks  (Anatidcu)  ;  but  the 
extension  of  the  bony  substance  of  the  jaws  into  tooth-like 
processes  is  an  entirely  unique  character,  in  which  it  stands 
quite  alone. 

The  known  Mammals  of  the  Mesozoic  period,  as  we  have 
seen,  are  all  of  small  size ;  and  with  one  not  unequivocal 
exception,  they  appear  to  be  referable  to  the  order  of  the 


THE  EOCENE  PERIOD.  309 

Pouched  Quadrupeds  (Marsupials),  almost  the  lowest  group 
of  the  whole  class  of  the  Mammalia.  In  the  Eocene  rocks, 
on  the  other  hand,  numerous  remains  of  Quadrupeds  have 
been  brought  to  light,  representing  most  of  the  great  Mam- 
malian orders  now  in  existence  upon  the  earth,  and  in  many 
cases  indicating  animals  of  very  considerable  dimensions.  We 
are,  in  fact,  in  a  position  to  assert  that  the  majority  of  the 
great  groups  of  Quadrupeds  with  which  we  are  familar  at  the 
present  day  were  already  in  existence  in  the  Eocene  period, 
and  that  their  ancient  root-stocks  were  even  in  this  early  time 
separated  by  most  of  the  fundamental  differences  of  structure 
which  distinguish  their  living  representatives.  At  the  same 
time,  there  are  some  amongst  the  Eocene  quadrupeds  which 
have  a  "  generalized "  character,  and  which  may  be  regarded 
as  structural  types  standing  midway  between  groups  now 
sharply  separated  from  one  another. 

The  order  of  the  Marsupials — including  the  existing  Kan- 
garoos, Wombats,  Opossums,  Phalangers,  &c. — is  poorly 
represented  in  deposits  of  Eocene  age.  The  most  celebrated 
example  of  this  group  is  the  Didelphys  gypsorum  of  the 
Gypseous  beds  of  Montmartre,  near  Paris,  an  Opossum  very 
nearly  allied  to  the  living  Opossums  of  North  and  South 
America. 

No  member  of  the  Edentates  (Sloths,  Ant-eaters,  and  Arma- 
dillos) has  hitherto  been  detected  in  any  Eocene  deposit. 
The  aquatic  order  of  the  Sirenians  (Dugongs  and  Manatees), 
with  their  fish-like  bodies  and  tails,  paddle-shaped  fore- 
limbs,  and  wholly  deficient  hind-limbs,  are  represented  in 
strata  of  this  age  by  remains  of  the  ancient  "  Sea-Cows, "  to 
which  the  name  of  Halitherium  has  been  applied.  Nearly 
allied  to  the  preceding  is  the  likewise  aquatic  order  of  the 
Whales  and  Dolphins  (Cetaceans),  in  which  the  body  is  also 
fish-like,  the  hind-limbs  are  wanting,  the  fore-limbs  are  con- 
verted into  powerful  "  flippers "  or  swimming-paddles,  and 
the  terminal  extremity  of  the  body  is  furnished  with  a 
horizontal  tail-fin.  Many  existing  Cetaceans  (such  as  the 
Whalebone  Whales)  have  no  true  teeth;  but  others  (Dol- 
phins, Porpoises,  Sperm  Whales)  possess  simple  conical  teeth. 
In  strata  of  Eocene  age,  however,  we  find  a  singular  group 
of  Whales  constituting  the  genus  Zeuglodon  (fig.  228),  in 
which  the  teeth  differed  from  those  of  all  existing  forms  in 
being  of  two  kinds, — the  front  ones  being  conical  incisors, 
whilst  the  back  teeth  or  molars  have  serrated  triangular 


3io  HISTORICAL  PALEONTOLOGY. 

crowns,  and  are  inserted  in  the  jaw  by  two  roots.  Each 
molar  (fig.  228,  A)  looks  as  if  it  were  composed  of  two 
separate  teeth  united  on  the  one  side  by  their  crowns;  and  it  is 
this  peculiarity  which  is  expressed  by  the  generic  name  (Gr. 
zeugle,  a  yoke;  odous,  tooth).  The  best-known  species  of 
the  genus  is  the  Zeuglodon  cetoides  of  Owen,  which  attained 
a  length  of  seventy  feet.  Remains  of  these  gigantic  Whales 
are  very  common  in  the  "  Jackson  Beds "  of  the  Southern 
United  States.  So  common  are  they  that,  according  to  Dana, 


Fig.  228.— Zeuglodon  cetoides.     A,  Molar  tooth  of    the  natural  size  ;  B,  Vertebra, 
reduced  in  size.    From  the  Middle  Eocene  of  the  United  States.    (After  Lyell.) 

"the  large  vertebrae,  some  of  them  a  foot  and  a  half  long  and 
a  foot  in  diameter,  were  formerly  so  abundant  over  the 
country,  in  Alabama,  that  they  were  used  for  making  walls,  or 
were  burned  to  rid  the  fields  of  them." 

The  great  and  important  order  of  the  Hoofed  Quadrupeds 
(Ungulata)  is  represented  in  the  Eocene  by  examples  of  both 
of  its  two  principal  sections — namely,  those  with  an  uneven 
number  of  toes  (one  or  three)  on  the  foot  (Perissodactyle  Ungu- 
lates), and  those  with  an  even  number  of  toes  (two  or  four)  to 
each  foot  (Artiodactyle  Ungulates}.  Amongst  the  Odd-toed 
Ungulates,  the  living  family  of  the  Tapirs  (Tapiridce)  is  repre- 
sented by  the  genus  Coryphodon  of  Owen.  Nearly  related  to 
the  preceding  are  the  species  of  Palaotherium,  which  have 
a  historical  interest  as  being  amongst  the  first  of  the  Tertiary 
Mammals  investigated  by  the  illustrious  Cuvier.  Several 
species  of  Palaothere  are  known,  varying  greatly  in  size,  the 
smallest  being  little  bigger  than  a  hare,  whilst  the  largest  must 
have  equalled  a  good-sized  horse  in  its  dimensions.  The 
species  of  Palaotherium  appear  to  have  agreed  with  the 


THE  EOCENE  PERIOD.  311 

existing  Tapirs  in  possessing  a  lengthened  and  flexible  nose, 
which  formed  a  short  proboscis  or  trunk  (fig.  229),  suitable  as 
an  instrument  for  stripping  off  the  foliage  of  trees — the  char- 


Fig.  229. — Outline  of  PalcROthenum  magnum,  restored.    Upper  Eocene,  Europe. 
(After  Cuvier.) 

acters  of  the  molar  teeth  showing  them  to  have  been  strictly 
herbivorous  in  their  habits.  They  differ,  however,  from  the 
Tapirs,  amongst  other  characters,  in  the  fact  that  both  the 
fore  and  the  hind  feet  possessed  three  toes  each ;  whereas  in 
the  latter  there  are  four  toes  on  each  fore-foot,  and  the  hind- 
feet  alone  are  three-toed.  The  remains  of  Palaotheria  have 
been  found  in  such  abundance  in  certain  localities  as  to  show 
that  these  animals  roamed  in  great  herds  over  the  fertile  plains 
of  France  and  the  south  of  England  during  the  later  portion 
of  the  Eocene  period.  The  accompanying  illustration  (fig. 
229)  represents  the  notion  which  the  great  Cuvier  was  induced 
by  his  researches  to  form  as  to  the  outward  appearance  of 
Palceotherium  magnum.  Recent  discoveries,  however,  have 
rendered  it  probable  that  this  restoration  is  in  some  important 
respects  inaccurate.  Instead  of  being  bulky,  massive,  and 
more  or  less  resembling  the  living  Tapirs  in  form,  it  would  rather 
appear  that  Palceotherium  magnum  was  in  reality  a  slender, 
graceful,  and  long-necked  animal,  more  closely  resembling  in 
general  figure  a  Llama,  or  certain  of  the  Antelopes. 

The  singular  genus  Anchitherium  forms  a  kind  of  transition 
between  the  Palaotheria  and  the  true  Horses  (Equidcc').  The 
Horse  (fig.  230,  D)  possesses  but  one  fully-developed  toe  to 


312 


HISTORICAL  PALEONTOLOGY. 


each  foot,  this  being  terminated  by  a  single  broad  hoof,  and 
representing  the  middle  toe — the  third  of  the  typical  five- 
fingered  or  five-toed  limb  of  Quadrupeds  in  general.  In 
addition,  however,  to  this  fully-developed  toe,  each  foot  in 
the  horse  carries  two  rudimentary  toes  which  are  concealed 
beneath  the  skin,  and  are  known  as  the  "  splint-bones. " 
These  are  respectively  the  second  and  fourth  toes,  in  an 
aborted  condition ;  and  the  first  and  fifth  toes  are  wholly 
wanting.  In  Plipparion  (fig.  230,  C),  the  foot  is  essentially 
like  that  of  the  modern  Horses,  except  that  the  second  and 
fourth  toes  no  longer  are  mere  "  splint-bones, "  hidden  be- 
neath the  skin;  but  have  now  little  hoofs,  and  hang  freely, 
but  uselessly,  by  the  side  of  the  great  middle  toe,  not  being 
sufficiently  developed  to  reach  the  ground.  In  Anchitherium, 
again  (fig.  230,  B),  the  foot  is  three-toed,  like  that  of  Hipparion; 
but  the  two  lateral  toes  (the  second  and  fourth)  are  so  far 
developed  that  they  now  reach  the  ground.  The  first  digit 
(thumb  or  great  toe)  is  still  wanting;  as  also  is  the  fifth  digit 


..  4 


Fig.  230.— Skeleton  of  the  foot  In  various  forms  belonging  to  the  family  of  the  Equidce, 
A,  Foot  of  Orohippus,  Eocene  ;  B,  Foot  of  Anchitherium,  Upper  Eocene  and  Lower 
Miocene  ;  C,  Foot  of  Hipparion,  Upper  Miocene  and  Pliocene  ;  D,  Foot  of|  Horse 
(Equus),  Pliocene  and  Recent.  The  figures  indicate  the  numbers  of  the  digits  in  the 
typical  five-fingered  hand  of  Mammals .  (After  Marsh . ) 


(little  finger  or  little  toe).  Lastly,  the  Eocene  rocks  have 
yielded  in  North  America  the  remains  of  a  small  Equine 
quadruped,  to  which  Marsh  has  given  the  name  of  Orohippus. 
In  this  singular  form — which  was  not  larger  than  a  fox — the 
foot  (fig.  230,  A)  carries  four  toes,  all  of  which  are  hoofed  and 
touch  the  ground,  but  of  which  the  third  toe  is  still  the  largest. 


THE  EOCENE  PERIOD.  313 

The  first  toe  (thumb  or  great  toe)  is  still  wanting;  but  in  this 
ancient  representative  of  the  Horses,  the  fifth  or  "little "  toe 
appears  for  the  first  time.  As  all  the  above-mentioned  forms 
succeed  one  another  in  point  of  time,  it  may  be  regarded  as 
probable  that  we  shall  yet  be  able  to  point,  with  some  cer- 
tainty, to  some  still  older  example  of  the  Equidcc,  in  which 


Fig.  231.— A noplotfierium  commune.    Eocene  Tertiary,  France.    ( After  Cuvier.) 

the   first   digit   is   developed,   and   the   foot   assumes   its   typical 
five-fingered  condition.* 

Passing  on  to  the  Even-toed  or  Artiodactyle  Ungulates,  no 
representative  of  the  Hippopotamus  seems  yet  to  have  existed, 
but  there  are  several  forms  (Charopotamus,  Hyopotamus,  &c.) 
more  or  less  closely  allied  to  the  Pigs  {Suida}  ;  and  the 
singular  group  of  the  Anoplotherida  may  be  regarded  as  form- 
ing a  kind  of  transition  between  the  Swine  and  the  Ruminants. 
The  Anoplotheria  (fig.  231)  were  slender  in  form,  the  largest 
not  exceeding  a  donkey  in  size,  with  long  tails,  and  having  the 
feet  terminated  by  two  hoofed  toes  each,  sometimes  with  a 
pair  of  small  accessory  hoofs  as  well.  The  teeth  exhibit  the 
peculiarity  that  they  are  arranged  in  a  continuous  series,  with- 
out any  gap  or  interval  between  the  molars  and  the  canines ;  and 
the  back  teeth,  like  those  of  all  the  Ungulates,  are  adapted  for 
grinding  vegetable  food,  their  crowns  resembling  in  form  those 
of  the  true  Ruminants.  The  genera  Dichobune  and  Xiphodon, 
of  the  Middle  and  Upper  Eocene,  are  closely  related  to 
Anoplotherium,  but  are  more  slender  and  deer-like  in  form. 
No  example  of  the  great  Ruminant  group  of  the  Ungulate 
Quadrupeds  has  as  yet  been  detected  in  deposits  of  Eocene 
age. 


314  HISTORICAL  PALEONTOLOGY. 

Whilst  true  Ruminants  appear  to  be  unknown,  the  Eocene 
strata  of  North  America  have  yielded  to  the  researches  of 
Professor  Marsh  examples  of  an  extraordinary  group  (Dino- 
cerata),  which  may  be  considered  as  in  some  respects  inter- 
mediate between  the  Ungulates  and  the  Proboscideans.  In 
Dinoceras  itself  (fig.  232)  we  have  a  large  animal,  equal  in 
dimensons  to  the  living  Elephants,  which  it  further  resembles 
in  the  structure  of  the  massive  limbs,  except  that  there  are 
only  four  toes  to  each  foot.  The  upper  jaw  was  devoid  of 
front  teeth,  but  there  were  two  very  large  canine  teeth,  in  the 
form  of  tusks  directed  perpendicularly  downwards ;  and  there 
was  also  a  series  of  six  small  molars  on  each.  Each  upper 
jaw-bone  carried  a  bony  projection,  which  was  probably  of  the 
nature  of  a  "  horn-core, "  and  was  originally  sheathed  in  horn. 


Fig.  232.— Skull  of  Dinoceras  mirabilis,  greatly  reduced.    Eocene,  North  America. 
(After  Marsh.) 


Two  similar,  but  smaller,  horn-cores  are  carried  on  the  nasal 
bones;  and  two  much  larger  projections,  also  probably  of  the 
nature  of  horn-cores,  were  carried  upon  the  forehead.  We 
may  thus  infer  that  Dinoceras  possessed  three  pairs  of  horns, 


THE  EOCENE  PERIOD.  315 

all  of  which  resembled  the  horns  of  the  Sheep  and  Oxen  in 
consisting  of  a  central  bony  "  core,"  surrounded  by  a  horny 
sheath.  The  nose  was  not  prolonged  into  a  proboscis  or 
•'  trunk, "  as  in  the  existing  Elephants ;  and  the  tail  was  short 
and  slender.  Many  forms  of  the  Dinocerata  are  known ;  but  all 
these  singular  and  gigantic  quadrupeds  appear  to  have  been 
confined  to  the  North  American  continent,  and  to  be  restricted 
to  the  Eocene  period. 

The  important  order  of  the  Elephants  (Proboscidea)  is  also 
not  known  to  have  come  into  existence  during  the  Eocene 
period.  On  the  other  hand,  the  great  order  of  the  Beasts  of 
Prey  (Carnivora)  is  represented  in  Eocene  strata  by  several 
formations  belonging  to  different  types.  Thus  the  Arctocyon  pre- 


Fig.  233.— Portion  of  the  skeleton  of  Vespertilio  Parisiensis.    Eocene  Tertiary,  France. 

sents  us  with  an  Eocene  Carnivore  more  or  less  closely  allied 
to  the  existing  Racoons;  the  Palaonyctis  appears  to  be  related 
to  the  recent  Civet-cats ;  the  genus  Hy&nodon  is  in  some 
respects  comparable  to  the  living  Hysenas ;  and  the  Canis 
Parisiensis  of  the  gypsum-bearing  beds  of  Montmartre  may 
perhaps  be  allied  to  the  Foxes. 

The  order  of  the  Bats  (Cheiroptera}  is  represented  in  Eocene 
strata  of  the  Paris  basin  (Gypseous  series  of  Montmartre)  by 
the  Vespertilio  Parisiensis  (fig.  233),  an  insect-eating  Bat  very 


316  HISTORICAL  PALEONTOLOGY. 

similar  to  some  of  the  existing  European  forms.  Lastly,  the 
Eocene  deposits  have  yielded  more  or  less  satisfactory  evi- 
dence of  the  existence  in  Europe  at  this  period  of  examples  of 
the  orders  of  the  Gnawing  Mammals  (Rodentia),  the  Insect- 
eating  Mammals  (Insectivora),  and  the  Monkeys  (Quadru- 
mana).  * 


CHAPTER  XIX. 
THE  MIOCENE  PERIOD. 

The  Miocene  rocks  comprise  those  Tertiary  deposits  which 
contain  less  than  about  35  per  cent  of  existing  species  of  shells 
(Molluscd),  and  more  than  5  per  cent — or  those  deposits  in 
which  the  proportion  of  living  shells  is  less  than  of  extinct 
species.  They  are  divisible  into  a  Lower  Miocene  (Oligocene) 
and  an  Upper  Miocene  series. 

In  Britain,  the  Miocene  rocks  are  very  poorly  developed, 
one  of  their  leading  developments  being  at  Bovey  Tracy  in 
Devonshire,  where  there  occur  sands,  clays,  and  beds  of  lignite 
or  imperfect  coal.  These  strata  certain  numerous  plants, 
amongst  which  are  Vines,  Figs,  the  Cinnamon-tree,  Palms, 
and  many  Conifers,  especially  those  belonging  to  the  genus 
Sequoia  (the  "Red-woods").  These  Bovey  Tracy  lignites  are 
of  Lower  Miocene  age,  and  they  are  lacustrine  in  origin.  Also 
of  Lower  Miocene  age  are  the  so-called  "  Hempstead  Beds " 
of  Yarmouth  in  the  Isle  of  Wight.  These  attain  a  thickness  of 
less  than  200  feet,  and  are  shown  by  their  numerous  fossils  to 
be  principally  a  true  marine  formation.  Lastly,  the  Duke  of 
Argyll,  in  1851,  showed  that  there  existed  at  Ardtun,  in  the 
island  of  Mull,  certain  Tertiary  strata  containing  numerous 
remains  of  plants ;  and  these  also  are  now  regarded  as  belong- 
ing to  the  Lower  Miocene. 

*  A  short  list  of  the  more  important  works  relating  to  the  Eocene 
rocks  and  fossils  will  be  given  after  all  the  Tertiary  deposits  have  been 
treated  of. 


THE  MIOCENE  PERIOD.  317 

In  France,  the  Lower  Miocene  is  represented  in  Auvergne, 
Cantal,  and  Velay,  by  a  great  thickness  of  nearly  horizontal 
strata  of  sands,  sandstone,  clays,  marls,  and  limestones,  the 
whole  of  fresh-water  origin.  The  principal  fossils  of  these 
lacustrine  deposits  are  Mammalia,  of  which  the  remains  occur 
in  great  abundance.  In  the  valley  of  the  Loire  occur  the 
typical  European  deposits  of  Upper  Miocene  age.  These  are 
known  as  the  "  Faluns, "  from  a  provincial  term  applied  to 
shelly  sands,  employed  to  spread  upon  soils  which  are  deficient 
in  lime;  and  the  Upper  Miocene  is  hence  sometimes  spoken 
of  as  the  "  Falunian "  formation.  The  Faluns  occur  in  scat- 
tered patches,  which  are  rarely  more  than  50  feet  in  thickness, 
and  consist  of  sands  and  marls.  The  fossils  are  chiefly  marine ; 
but  there  occur  also  land  and  fresh-water  shells,  together  with 
the  remains  of  numerous  Mammals.  About  25  per  cent  of  the 
shells  of  the  Faluns  are  identical  with  existing  species.  The 
sands,  limestones,  and  marls  of  the  Department  of  Gers,  near 
the  base  of  the  Pyrenees,  rendered  famous  by  the  number  of 
Mammalian  remains  exhumed  from  them  by  M.  Lartet,  also 
belong  to  the  age  of  the  Faluns. 

In  Switzerland,  between  the  Alps  and  the  Jura,  there  occurs 
a  great  series  of  Miocene  deposits,  known  collectively  as  the 
"  Molasse, "  from  the  soft  nature  of  a  greenish  sandstone, 
which  constitutes  one  of  its  chief  members.  It  attains  a  thick- 
ness of  many  thousands  of  feet,  and  rises  into  lofty  mountains, 
some  of  which — as  the  Rigi — are  more  than  6000  feet  in 
height.  The  middle  portion  of  the  Molasse  is  of  marine 
origin,  and  is  shown  by  its  fossils  to  be  of  the  age  of  the 
Faluns;  but  the  lower  and  upper  portions  of  the  formation 
are  mainly  or  entirely  of  fresh-water  origin.  The  Lower 
Molasse  (of  Lower  Miocene  age)  has  yielded  about  500  species 
of  plants,  mostly  of  tropical  or  sub-tropical  forms.  The  Upper 
Molasse  has  yielded  about  the*  same  number  of  plants,  with 
about  900  species  of  Insects,  such  as  wood-eating  Beetles, 
Water-beetles,  White  Ants,  Dragon-flies,  &c. 

In  Belgium,  strata  of  both  Lower  and  Upper  Miocene  age 
are  known, — the  former  (Rupelian  Clays}  containing  numerous 
marine  fossils;  whilst  the  latter  (Bolderberg  Sands)  have 
yielded  numerous  shells  corresponding  with  those  of  the 
Faluns. 

In  Austria,  Miocene  strata  are  largely  developed,  marine 
beds  belonging  to  both  the  Lower  and  Upper  division  of  the 
formation  occurring  extensively  in  the  Vienna  basin.  The 


318  HISTORICAL  PALAEONTOLOGY. 

well-known  Brown  Coals  of  Radaboj,  in  Croatia,  with  numer- 
ous plants  and  insects,  are  also  of  Lower  Miocene  age. 

In  Germany,  deposits  belonging  to  both  the  Lower  and 
Upper  division  of  the  Miocene  formation  are  extensively  de- 
veloped. To  the  former  belong  the  marine  strata  of  the  May- 
ence  basin,  and  the  marine  Rupelian  Clay  near  Berlin ;  whilst 
a  celebrated  group  of  strata  belonging  to  the  Upper  Miocene 
occurs  near  Epplesheim,  in  Hesse-Darmstadt,  and  is  well 
known  for  the  number  of  its  Mammalian  remains. 

In  Greece,  at  Pikerme,  near  Athens,  there  occurs  a  celebrated 
deposit  of  Upper  Miocene  age,  well  known  to  palaeontologists 
through  the  researches  of  M.  M.  Wagner,  Roth,  and  Gaudry 
upon  the  numerous  Mammalia  which  it  contains.  In  Italy, 
also,  strata  of  both  Lower  and  Upper  Miocene  age  are  well 
developed  in  the  neighborhood  of  Turin. 

In  the  Siwalik  Hills,  in  India,  at  the  southern  foot  of  the 
Himalayas,  occurs  a  series  of  Upper  Miocene  strata,  which 
have  become  widely  celebrated  through  the  researches  of  Dr. 
Falconer  and  Sir  Proby  Cautley  upon  the  numerous  remains 
of  Mammals  and  Reptiles  which  they  contain.  Beds  of  corre- 
sponding age,  with  similar  fossils,  are  known  to  occur  in  the 
island  of  Perim  in  the  Gulf  of  Cambay. 

Lastly,  Miocene  deposits  are  found  in  North  America,  in 
New  Jersey,  Maryland,  Virginia,  Missouri,  California,  Oregon, 
&c.,  attaining  a  thickness  of  1500  feet  or  more.  They  consist 
principally  of  clays,  sands,  and  sandstones,  sometimes  of 
marine  and  sometimes  of  fresh-water  origin.  Near  Richmond, 
in  Virginia,  there  occurs  a  remarkable  stratum,  wrongly  called 
"  Infusorial  Earth, "  which  is  occasionally  30  feet  in  thickness, 
and  consists  almost  wholly  of  the  siliceous  envelopes  of  cer- 
tain low  forms  of  plants  (Diatoms),  along  with  the  spicules  of 
Sponges  and  other  siliceous  organisms  (see  fig.  16).  The 
White  River  Group  of  Hayden  occurs  in  the  Upper  Missouri 
region,  and  is  largely  exposed  over  the  barren  and  desolate 
district  known  as  the  "  Mauvaises  Terres. "  They  have  a 
thickness  of  1000  feet  or  more,  and  contain  numerous  remains 
of  Mammals.  They  are  of  lacustrine  origin,  and  are  believed 
to  be  of  the  age  of  the  Lower  Miocene.  Upon  the  whole, 
about  from  15  to  30  per  cent  of  the  Mollusca  of  the  American 
Miocene  are  identical  with  existing  species. 

In  addition  to  the  regions  previously  enumerated,  Miocene 
strata  are  known  to  be  developed  in  Greenland,  Iceland,  Spits- 
bergen, and  in  other  areas  of  less  importance. 


THE  MIOCENE  PERIOD. 


319 


The  life  ot  the  Miocene  period  is  extremely  abundant,  and, 
from  the  nature  of  the  deposits  of  this  age,  also  extremely 
varied  in  its  character.  The  marine  beds  of  the  formation 
have  yielded  numerous  remains  of  both  Vertebrate  and  Inver- 
tebrate sea-animals;  whilst  the  fresh-water  deposits  contain 
the  skeletons  of  such  shells,  fishes,  &c.,  as  now  inhabit  rivers 
or  lakes.  Both  the  marine  and  the  lacustrine  beds  have  been 
shown  to  contain  an  enormous  number  of  plants,  the  latter 
more  particularly;  whilst  the  Brown  Coals  of  the  format  im 
are  made  up  of  vegetable  matter  little  altered  from  its  original 
condition.  The  remains  of  air-breathing  animals,  such  as 
Insects,  Reptiles,  Birds,  and  Mammals,  are  also  abundantly 
found,  more  especially  in  the  fresh-water  beds. 

The  plants  of  the  Miocene  period  are  extraordinarily  num- 
erous, and  only  some  of  the  general  features  of  the  vegetation  of 
this  epoch  can  be  indicated  here.  Our  chief  sources  of  informa- 
tion as  to  the  Miocene  plants  are  the  Brown  Coals  of  Germany 
and  Austria,  the  Lower  and  Upper  Molasse  of  Switzerland, 
and  the  Miocene  strata  of  the  Arctic  regions.  The  lignites  of 
Austria  have  yielded  very  numerous  plants,  chiefly  of  a  tropical 
character — one  of  the  most  noticeable  forms  being  a  Palm  of 


Fig.  234.— Miocene  Palms.    A,  Chamcerops  Helvetica  ;  B,  Sabal  major. 
Lower  Miocene  of  Switzerland  and  France. 

the  genus  Sabal  (fig.  234,  B),  now  found  in  America.  The 
plants  of  the  Lower  Miocene  of  Switzerland  are  also  mostly 
of  a  tropical  character,  but  include  several  forms  now  found 
in  North  America,  such  as  a  Tulip-tree  {Liriodendron}  and  a 
Cypress  (Taxodium}.  Amongst  the  more  remarkable  forms 
from  these  beds  may  be  mentioned  Fan-Palms  (Chauiarops, 
fig.  234,  A),  numerous  tropical  ferns,  and  two  species  of  Cin- 


320 


HISTORICAL  PALEONTOLOGY. 


namon.  The  plant-remains  of  the  Upper  Molasse  of  Switzer- 
land indicate  an  extraordinarily  rank  and  luxuriant  vegetation, 
composed  mainly  of  plants  which  now  live  in  warm  countries. 
Among  the  commoner  plants  of  this  formation  may  be  enumer- 
ated many  species  of  Maple  (Acer),  Plane-trees  (Platanus 


Fig.  235.— Platanus  aceroides,  an 
Upper  Miocene  Plane-tree.  «,  Leaf  ; 
b,  The  core  of  a  bundle  of  fruits  ;  c, 
A  single  fruit. 


Fig.  236.  —  Cinnamo- 
mum  polymorphum.  a, 
Leaf  ;  6,  Flower.  Upper 
Miocene. 


fig.  235),  Cinnamon-trees  (fig.  236),  and  other  members  of  the 
Lauracece,  many  species  of  Proteacea  (Banksia,  Grevillea,  &c.), 
several  species  of  Sarsaparilla  (Smilax),  Palms,  Cypresses,  &c. 

In  Britain,  the  Lower  Miocene  strata  of  Bovey  Tracy  have 
yielded  remains  of  Ferns,  Vines,  Fig,  Cinnamon,  Proteaceaz, 
&c.,  along  with  numerous  Conifers.  The  most  abundant  of 
these  last  is  a  gigantic  pine — the  Sequoia  Couttsia — which  is 
very  nearly  allied  to  the  huge  Sequoia  (W  ellingtonia)  gigantea 
of  California.  A  nearly-allied  form  (Sequoia  Langsdorffi}  has 
been  detected  in  the  leaf-bed  of  Ardtun,  in  the  Hebrides. 

In  Greenland,  as  well  as  in  other  parts  of  the  Arctic  regions, 
Miocene  strata  have  been  discovered  which  have  yielded  a 
great  number  of  plants,  many  of  which  are  identical  with 
species  found  in  the  European  Miocene.  Amongst  these 
plants  are  found  many  trees,  such  as  Conifers,  Beeches,  Oaks, 
Maples,  Plane-trees,  Walnuts,  Magnolias,  &c.,  with  numerous 
shrubs,  ferns,  and  other  smaller  plants.  With  regard  to  the 
Miocene  flora  of  the  Arctic  regions,  Sir  Charles  Lyell  remarks 
that  "more  than  thirty  species  of  Coniferse  have  been  found, 
including  several  Sequoias  (allied  to  the  gigantic  Wellingtonia 
of  California),  with  species  of  Thujopsis  and  Salisburia,  now 


THE  MIOCENE  PERIOD.  321 

peculiar  to  Japan.  There  are  also  beeches,  oaks,  planes, 
poplars,  maples,  walnuts,  limes,  and  even  a  magnolia,  two 
cones  of  which  have  recently  been  obtained,  proving  that 
this  splendid  evergreen  not  only  lived  but  ripened  its  fruit 
within  the  Arctic  circle.  Many  of  the  limes,  planes,  and 
oaks  were  large-leaved  species ;  and  both  flowers  and  fruits, 
besides  immense  quantities  of  leaves,  are  in  many  cases  pre- 
served. Among  the  shrubs  are  many  evergreens,  as  Andro- 
meda, and  two  extinct  genera,  Daphnogene  and  M'Clintockia, 
with  fine  leathery  leaves,  together  with  hazel,  blackthorn, 
holly,  logwood,  and  hawthorn.  A  species  of  Zamia  (Zamites) 
grew  in  the  swamps,  with  Potanwgeton,  Sparganium,  and 
Menyanthes;  while  ivy  and  vines  twined  around  the  forest- 
trees,  and  the  broad-level  ferns  grew  beneath  their  shade.  Even 
in  Spitzbergen,  as  far  north  as  lat.  78°  56',  no  less  than  ninety- 
five  species  of  fossil  plants  have  been  obtained,  including 
Taxodium  of  two  species,  hazel,  poplar,  alder,  beech,  plane- 
tree,  and  lime.  Such  a  vigorous  growth  of  trees  within  12°  of 
the  pole,  where  now  a  dwarf  willow  and  a  few  herbaceous 
plants  form  the  only  vegetation,  and  where  the  ground  is 
covered  with  almost  perpetual  snow  and  ice,  is  truly  remark- 
able. " 

Taking  the  Miocene  flora  as  a  whole,  Dr.  Heer  concludes 
from  his  study  of  about  3000  plants  contained  in  the  Euro- 
pean Miocene  alone,  that  the  Miocene  plants  indicate  tropical 
or  sub-tropical  conditions,  but  that  there  is  a  striking  inter- 
mixture of  forms  which  are  at  present  found  in  countries 
widely  removed  from  one  another.  It  is  impossible  to  state 
with  certainty  how  many  of  the  Miocene  plants  belong  to 
existing  species,  but  it  appears  that  the  larger  number  are 
extinct.  According  to  Heer,  the  American  types  of  plants 
are  most  largely  represented  in  the  Miocene  flora,  next  those 
of  Europe  and  Asia,  next  those  of  Africa,  and  lastly  those  of 
Australia.  Upon  the  whole,  however,  the  Miocene  flora  of 
Europe  is  mostly  nearly  allied  to  the  plants  which  we  now 
find  inhabiting  the  warmer  parts  of  the  United  States ;  and 
this  has  led  to  the  suggestion  that  in  Miocene  times  the 
Atlantic  Ocean  was  dry  land,  and  that  a  migration  of  Ameri- 
can plants  to  Europe  was  thus  permitted.  This  view  is  borne 
out  by  the  fact  that  the  .Miocene  plants  of  Europe  are  most 
nearly  allied  to  the  living  plants  of  the  eastern  or  Atlantic 
seaboard  of  the  United  States,  and  also  by  the  occurrence  of 
a  rich  Miocene  flora  in  Greenland.  As  regards  Greenland, 
21 


322  HISTORICAL  PALEONTOLOGY. 

Dr.  Heer  has  determined  that  the  Miocene  plants  indicate  a 
temperate  climate  in  that  country,  with  a  mean  annual  tem- 
perature at  least  30°  warmer  than  it  is  at  present. 

The  present  limit  of  trees  is  the  isothermal  which  gives  the 
mean  temperature  of  50°  Fahr.  in  July,  or  about  the  parallel 
of  67°  N.  latitude.  In  Miocene  times,  however,  the  Limes, 
Cypresses,  and  Plane-trees  reach  the  79th  degree  of  latitude, 
and  the  Pines  and  Poplars  must  have  ranged  even  further 
north  than  this. 

The  Invertebrate  Animals  of  the  Miocene  period  are  very 
numerous,  but  they  belong  for  the  most  part  to  existing  types, 
and  they  can  only  receive  scanty  consideration  here.  The 
little  shells  of  Foratninifera  are  extremely  abundant  in  some 
beds,  the  genera  being  in  many  cases  such  as  now  flourish 
abundantly  in  our  seas.  The  principal  forms  belong  to  the 
genera  Textularia  (fig.  237),  Robulina,  Glandulina,  Poly- 
stomella,  Amplristegina,  &c. 
Corals  are  very  abundant, 
in  many  instances  forming 
regular  "  reefs  ;  "  but  all  the 
more  important  groups  are 
in  existence  at  the  present 
day.  The  Red  Coral  (Cor- 
allium'),  so  largely  sought 
after  as  an  ornamental  ma- 
terial, appears  for  the  first 

Fig.    237  .—Textularia    Meyeriana,    greatly 
time  in  deposits  of  this  age.  enlarged.    Miocene  Tertiary. 

Amongst   the  •  Echinoderms, 

we  meet  with  Heart-Urchins  (Spataugus),  Cake-Urchins 
(Scutella,  fig.  238),  and  various  other  forms,  the  majority  of 
which  are  closely  allied  to  forms  now  in  existence. 

Numerous  Crabs  and  Lobsters  represent  the  Crustacea;  but 
the  most  important  of  the  Miocene  Articulate  Animals  are  the 
Insects.  Of  these,  more  than  thirteen  hundred  species  have 
been  determined  by  Dr.  Heer  from  the  Miocene  strata  of 
Switzerland  alone.  They  include  almost  all  the  existing 
orders  of  insects,  such  as  numerous  and  varied  forms  of 
Beetles  (Coleoptera),  Forest-bugs  (Hemiptera},  Ants  (Hymen- 
optera),  Flies  (Diptera),  Termites  and  Dragon-flies  (Neurop- 
tera),  Grasshoppers  (Orthoptera),  and  Butterflies  (Lepidoptera}. 
One  of  the  latter,  the  well-known  Vanessa  Pluto  of  the  Brown 
Coals  of  Croatia,  even  exhibits  the  pattern  of  the  wing,  and  to 
some  extent  its  original  coloration;  whilst  the  more  durably- 


THE  MIOCENE  PERIOD.  323 

constructed   insects    are    often    in    a    state   of    exquisite    preser- 
vation. 

The  Mollusca  of  the  Miocene  period  are  very  numerous, 
but  call  for  little  special  comment.  Upon  the  whole,  they  are 
generically  very  similar  to  the  Shell-fish  of  the  present  day; 
whilst,  as  before  stated,  from  fifteen  to  thirty  per  cent  of  the 


Fig.  238.— Different  views  of  Scutella  svbrotnnda,  a  Miocene  "  Cake- Urchin ' 
from  the  south  of  France. 

species  are  identical  with  those  now  in  existence.  So  far  as  the 
European  area  is  concerned,  the  Molluscs  indicate  a  decidedly 
hotter  climate  than  the  present  one,  though  they  have  not  such 
a  distinctly  tropical  character  as  is  the  case  with  the  Eocene 
shells.  Thus  we  meet  with  many  Cones,  Volutes,  Cowries, 
Olive-shells,  Fig-shells,  and  the  like,  which  are  decidedly 
indicative  of  a  high  temperature  of  the  sea.  Polysoans  are 
abundant,  and  often  attain  considerable  dimensions ;  whilst 
Brachlopods,  on  the  other  hand,  are  few  in  number.  Bivalves 
and  Univalves  are  extremely  plentiful ;  and  we  meet  here  with 
the  shells  of  Winged-Snails  (Pteropods},  belonging  to  such 
existing  genera  as  Hyalea  (fig.  239)  and  Cleodora.  Lastly, 
the  Cephalofods  are  represent- 
ed both  by  the  chambered 
shells  of  Nautili  and  by  the 
internal  skeletons  of  Cuttle- 
fishes (Spirulirostra.} 

The  Fishes  of  the  Miocene  Fig.  239—  Different  views  of  the  shell 
period  are  very  abundant,  but  $£valM  Orb^an^  a  Miocene  ««o- 
of  little  special  importance. 

Besides  the  remains  of  Bony  Fishes,  we  meet  in  the  marine 
deposits  of  this  age  with  numerous  pointed  teeth  belonging 
to  different  kinds  of  Sharks.  Some  of  the  genera  of  these — 
such  as  Car  char  odon  (fig.  241),  Oxyrhina  (fig.  240),  Lamna, 
and  Galeocerdo — are  very  widely  distributed,  ranging  through 
both  the  Old  and  New  Worlds;  and  some  of  the  species  attain 
gigantic  dimensions. 


324  HISTORICAL  PALEONTOLOGY. 

Amongst  the  Amphibians  we  meet  with  distinctly  modern 
types,  such  as  Frogs  (Rana) 
and  Newts  or  Salamanders. 
The  most  celebrated  of  the 
latter  is  the  famous  Andrias 
Sclieuchzeri  (fig.  242),  dis- 
covered in  the  year  1725 
in  the  fresh-water  Miocene 
deposits  of  CEningen,  in 
Switzerland.  The  skeleton 
indicates  an  animal  nearly 
five  feet  in  length;  and  it  Fig.  240.  -  Tooth  rig,  241.  -  Tooth 

.    .  of    Oxyrhina    xiph-        of  Carcharodon  pro- 

was   originally  described  by        odon.    Miocene.  ductus.    Miocene. 

Scheuchzer,  a  Swiss  physi- 
cian, in  a  dissertation  published  in  1731,  as  the  remains  of  one 
of  the  human  beings  who  were  in  existence  at  the  time  of  the 
Noachian  Deluge.  Hence  he  applied  to  it  the  name  of  Homo 
diluv'n  test  is.  In  reality,  however,  as  shown  by  Cuvier,  we 
have  here  the  skeleton  of  a  huge  Newt,  very  closely  allied  to 
the  Giant  Salamander  (Menopoma  maxima}  of  Java. 

The  remains  of  Reptiles  are  far  from  uncommon  in  the 
Miocene  rocks,  consisting  principally  of  Chelonians  and  Cro- 
codilians.  The  Land-tortoises  (Tcstudinidce}  make  their  first 
appearance  during  this  period.  The  most  remarkable  form 
of  this  group  is  the  huge  Colossochelys  Atlas  of  the  Upper 
Miocene  deposits  of  the  Siwalik  Hills  in  India,  described  by 
Dr.  Falconer  and  Sir  Proby  Cautley.  Far  exceeding  any 
living  Tortoise  in  its  dimensions,  this  enormous  animal  is 
estimated  as  having  had  a  length  of  about  twenty  feet,  measured 
from  the  tip  of  the  snout  to  the  extremity  of  the  tail,  and 
to  have  stood  upwards  of  seven  feet  high.  All  the  details  of  its 
organization,  however,  prove  that  it  must  have  been  "  strictly 
a  land  animal,  with  herbivorous  habits,  and  probably  of  the 
most  inoffensive  nature. "  The  accomplished  palaeontologist 
just  quoted,  shows  further  that  some  of  the  traditions  of  the 
Hindoos  would  render  it  not  improbable  that  this  colossal 
Tortoise  had  survived  into  the  earlier  portion  of  the  human 
period. 

Of  the  Birds  of  the  Miocene  period  it  is  sufficient  to  re- 
mark that  though  specifically  distinct,  they  belong,  so  far  as 
known,  wholly  to  existing  groups,  and  therefore  present  no 
points  of  special  palasontological  interest. 

The  Mammals  of  the  Miocene  are  very  numerous,  and  only 


THE  MIOCENE  PERIOD.  325 


242  —Front  portion  of  the  skeleton  of  Andrias  Scheuclizeri,  a  Giant  Salamander 
from  the  Miocene  Tertiary  of  (Eningen,  In  Switzerland.    Reduced  in  size. 


326  HISTORICAL  PALEONTOLOGY. 

the  more  important  forms  can  be  here  alluded  to.  Amongst 
the  Marsupials,  the  Old  World  still  continued  to  possess 
species  of  Opossum  (Didephys),  allied  to  the  existing  American 
forms.  The  Edentates  (Sloths,  Armadillos,  and  Ant-eaters),  at 
the  present  day  mainly  South  American,  are  represented  by 
two  large  European  forms.  One  of  these  is  the  large  Macro- 
thcrium  giganteum  of  the  Upper  Miocene  of  Gers  in  Southern 
France,  which  appears  to  have  been  in  many  respects  allied  to 
the  existing  Scaly  Ant-eaters  or  Pangolins,  at  the  same  time 
that  the  disproportionately  long  fore-limbs  would  indicate  that 
it  possessed  the  climbing  habits  of  the  Sloths.  The  other  is 
the  still  more  gigantic  Ancylotherium  Pentelici  of  the  Upper 
Miocene  of  Pikerme,  which  seems  to  have  been  as  large  as,  or 
larger  than,  the  Rhinoceros,  and  which  must  have  been  terres- 
trial in  its  habits.  This  conclusion  is  further  borne  out  by  the 
comparative  equality  of  length  which  subsists  between  the  fore 
and  hind  limbs,  and  is  not  affected  by  the  curvature  and 
crookedness  of  the  claws,  this  latter  feature  being  well  marked 
in  such  existing  terrestrial  Edentates  as  the  Great  Ant-eater. 

,  The  aquatic  Sirenians  and  Cetaceans  are  represented  in 
Miocene  times  by  various  forms  of  no  special  importance. 
Amongst  the  former,  the  previously  existing  genus  Halitherium 
continued  to  survive,  and  amongst  the  latter  we  meet  with 
remains  of  Dolphins  and  of  Whales  of  the  "  Zeuglodont " 
family.  We  may  also  note  here  the  first  appearance  of  true 
"  Whalebone  Whales,"  two  species  of  which,  resembling  the 
living  "  Right  Whale "  of  Arctic  seas,  and  belonging  to  the 
same  genus  (Balana),  have  been  detected  in  the  Miocene 
beds  of  North  America. 

The  great  order  of  the  Ungulates  or  Hoofed  Quadrupeds  is 
very  largely  developed  in  strata  of  Miocene  age,  various  new 
types  of  this  group  making  their  appearance  here  for  the  first 
time,  whilst  some  of  the  characteristic  genera  of  the  preceding 
period  are  still  represented  under  new  shapes.  Amongst  the 
Odd-toed  or  "  Perissodactyle  "  Ungulates,  we  meet  for  the  first 
time  with  representatives  of  the  family  Rhino cerida  compris- 
ing only  the  existing  Rhinoceroses.  In  India  in  the  Upper 
Miocene  beds  of  the  Sikalik  Hills,  and  in  North  America, 
several  species  of  Rhinoceros  have  been  detected,  agreeing  with 
the  existing  forms  in  possessing  three  toes  to  each  foot,  and  in 
having  one  or  two  solid  fibrous  "horns"  carried  upon  the  front 
of  the  head.  On  the  other  hand,  the  forms  of  this  group  which 
distinguish  the  Miocene  deposits  of  Europe  appear  to  have 


THE  MIOCENE  PERIOD.  327 

been    for    the   most   part   hornless,    and    to    have    resembled    the 
Tapirs  in  having  three-toed  hind-feet,  but  four-toed  fore-feet. 

The  family  of  the  Tapirs  is  represented,  both  in  the  Old 
and  New  Worlds,  by  species  of  the  genus  Lophiodon,  some  of 
which  were  quite  diminutive  in  point  of  size,  whilst  others 
attained  the  dimensions  of  a  horse.  Nearly  allied  to  this 
family,  also,  is  the  singular  group  of  quadrupeds  which  Marsh 
has  described  from  the  Miocene  strata  of  the  United  States 
under  the  name  of  Brontotheridcr.  These  extraordinary  ani- 
mals, typified  by  Brontnthcrium  (fig.  243)  itself,  agree  with  the 


Fig.  243.— Skull  of  Brontotherium  ingem.    Miocene  Tertiary,  United  States. 
(After  Marsh.) 

existing  Tapirs  of  South  America  and  the  Indian  Archipelago 
in  having  the  fore-feet  four-toed,  whilst  the  hind-feet  are  three- 
toed  ;  and  a  further  point  of  resemblance  is  found  in  the  fact 
(as  shown  by  the  form  of  the  nasal  bones)  that  the  nose  was 
long  and  flexible,  forming  a  short  movable  proboscis  or  trunk, 
by  means  of  which  the  animal  was  enabled  to  browse  on 
shrubs  or  trees.  They  differ,  however,  from  the  Tapirs,  not 
only  in  the  apparent  presence  of  a  long  tail,  but  also  in  the 
possession  of  a  pair  of  very  large  "  horn-cores,  "  carried  upon 
the  nasal  bones,  indicating  that  the  animal  possessed  horns  of 
a  similar  structure  to  those  of  the  "  Hollow-horned "  Rumin- 
ants (e.  g.,  Sheep  and  Oxen).  Brontotherium  gigas  is  said  to  be 
nearly  as  large  as  an  Elephant,  whilst  B.  ingens  appears  to 
have  attained  dimensions  still  more  gigantic.  The  well-known 
genus  Titan otheriunt  of  the  American  Miocene  would  also 
appear  to  belong  to  this  group. 

The  family  of  the  Horses   (Equidcr}   appears  under  various 
forms  in  the  Miocene,  but  the  most  important  and  best  known 


328  HISTORICAL  PALAEONTOLOGY. 

of  these  is  Hipparion.  In  this  genus  the  general  conformation 
of  the  skeleton  is  extremely  similar  to  that  of  the  existing 
Horses,  and  the  external  appearance  of  the  animal  must  have 
been  very  much  the  same.  The  foot  of  Hipparion,  however, 
as  has  been  previously  mentioned,  differed  from  that  of  the 
Horse  in  the  fact  that  whilst  both  possess  the  middle  toe  greatly 
developed  and  enclosed  in  a  broad  hoof,  the  former,  in  addition, 
possessed  two  lateral  toes,  which  were  sufficiently  developed 
to  carry  hoofs,  but  were  so  far  rudimentary  that  they  hung  idly 
by  the  side  of  the  central  toe  without  touching  the  ground 
(see  fig.  230).  In  the  Horse,  on  the  other  hand,  these  lateral 
toes,  though  present,  are  not  only  functionally  useless,  but  are 
concealed  beneath  the  skin.  Remains  of  the  Hipparion  have 
been  found  in  various  regions  in  Europe  and  in  India;  and 
from  the  immense  quantities  of  their  bones  found  in  certain 
localities,  it  may  be  safely  inferred  that  these  Middle  Tertiary 
ancestors  of  the  Horses  lived,  like  their  modern  representa- 
tives, in  great  herds,  and  in  open  grassy  plains  or  prairies. 

Amongst  the  Even-toed  or  Artiodactyle  Ungulates,  we  for 
the  first  time  meet  with  examples  of  the  Hippopotamus,  with  its 
four-toed  feet,  its  massive  body,  and  huge  tusk-like  lower 
canine  teeth.  The  Miocene  deposits  of  Europe  have  not 
hitherto  yielded  any  remains  of  Hippopotamus;  but  several 
species  have  been  detected  in  the  Upper  Miocene  of  the  Siwalik 
Hills  by  Dr.  Falconer  and  Sir  Proby  Cautley.  These  ancient 
Indian  forms,  however,  differ  from  the  existing  Hippopotamus 
amphibius  of  Africa  in  the  fact  that  they  possessed  six  incisor 
teeth  in  each  jaw  (fig.  244),  whereas  the  latter  has  only  four. 

Amongst  the  other  Even-toed  Ungulates,  the  family  of  the 
Pigs  (Suida)  is  represented  by  true  Swine  (Sus  EryuwntJiius), 
Peccaries  (Dicotyles  antiquus},  and  by  forms  which,  like  the 
great  Elotherium  of  the  American  Miocene,  have  no  represen- 
tative at  the  present  day.  The  Upper  Miocene  of  India  has 
yielded  examples  of  the  Camels.  Small  Musk-deer  (AmpJii- 
tragulus  and  Dremotheriuin}  are  known  to  have  existed  in 
France  and  Greece;  and  the  true  Deer  (Cervidcc},  with  their 
solid  bony  antlers,  appear  for  the  first  time  here  in  the  person  of 
species  allied  to  the  living  Stags  (Cervus),  accompanied  by  the 
extinct  genus  Dorcatherium.  The  Giraffes  (Camelopardalidce'), 
now  confined  to  Africa,  are  known  to  have  lived  in  India  and 
Greece;  and  the  allied  Helladotherium,  in  some  respects  inter- 
mediate between  the  Giraffes  and  the  Antelopes,  ranged  over 
Southern  Europe  from  Attica  to  France.  The  great  group  of 


THE  MIOCENE  PERIOD. 


329 


the  "Hollow-horned"  Ruminants  (Cavicornia},  lastly,  came 
into  existence  in  the  Miocene  period;  and  though  the  typical 
families  of  the  Sheep  and  Oxen  are  apparently  wanting,  there 
are  true  Antelopes,  together  with  forms  which,  if  systematic- 


rig.  244.-  a,  Skull  of  Hippopotamus  Sivalerwis,  viewed  from  below,  one-eighth  of 
the  natural  size  ;  b,  Molar  tooth  of  the  same,  showing  the  surface  of  the  crown,  one- 
half  of  the  natural  size ;  c,  Front  of  the  lower  jaw  of  the  same,  showing  the  six  incisors 
and  the  tusk-like  canines,  one-eighth  of  the  natural  size.  Upper  Miocene,  Siwulik 
Hills.  (After  Falconer'and  Cautley.) 


ally  referable  to  the  Antilopida,  nevertheless  are  more  or  less 
clearly  transitional  between  this  and  the  family  of  the  Sheep 
and  Goats.  Thus  the  Palaoreas  of  the  Upper  Miocene  of 
Greece  may  be  regarded  as  a  genuine  Antelope;  but  the 
Tragoceras  of  the  same  deposit  is  intermediate  in  its  characters 
between  the  typical  Antelopes  and  the  Goats.  Perhaps  the 
most  remarkable,  however,  of  these  Miocene  Ruminants  is  the 
Sivatherium  giganteum  (fig.  245)  of  the  Siwalik  Hills,  in  India. 
In  this  extraordinary  animal  there  were  two  pairs  of  horns, 
supported  by  bony  "  horn-cores, "  so  that  there  can  be  no 
hesitation  in  referring  Sivatherium  to  the  Cavicorn  Rumin- 
ants. If  all  these  horns  had  been  simple,  there  would  have 


330  HISTORICAL  PALAEONTOLOGY. 

been  no  difficulty  in  considering  Sivatherium  as  simply  a 
gigantic  four-horned  Antelope,  essentially  similar  to  the  living 
Antilope  (Tetraceros)  quadriconiis  of  India.  The  hinder  pair 
of  horns,  however,  is  not  only  much  larger  than  the  front  pair, 
but  each  possesses  two  branches  or  snags — a  peculiarity  not  to 
be  paralleled  amongst  any  existing  Antelope,  save  the  abnormal 
Prongbuck  (Antilocapra)  of  North  America.  Dr.  Murie,  how- 
ever, in  an  admirable  memoir  on  the  structure  and  relationships 
of  Sivatherium,  has  drawn  attention  to  the  fact  that  the  Prong- 


Fig.  245.— Skull  of  Sivat/teriain  giganteum,  reduced  In  size.    Miocene,  India. 
(After  Murie.) 

buck  sheds  the  sheath  of  its  horns  annually,  and  has  suggested 
that  this  may  also  have  been  the  case  with  the  extinct  form. 
This  conjecture  is  rendered  probable,  amongst  other  reasons, 
by  the  fact  that  no  traces  of  a  horny  sheath  surrounding  the 
horn-cores  of  the  Indian  fossil  have  been  as  yet  detected. 
Upon  the  whole,  therefore,  we  may  regard  the  elephantine 
Sivatherium  as  being  most  nearly  allied  to  the  Prongbuck  of 
Western  America,  and  thus  as  belonging  to  the  family  of  the 
Antelopes, 


THE  MIOCENE  PERIOD. 


It  is  to  the  Miocene  period,  again,  to  which  we  must  refer 
the  first  appearance  of  the  important  order  of  the  Elephants 
and  their  allies  (Proboscideans),  all  of  which  are  characterized 
by  their  elongated  trunk-like  noses,  the  possession  of  five  toes  to 
the  foot,  the  absence  of  canine  teeth,  the  development  of  two 
or  more  of  the  incisor  teeth  into  long  tusks,  and  the  adaptation 
of  the  molar  teeth  to  a  vegetable  diet.  Only  three  generic 
groups  of  this  order  are  known — namely,  the  extinct  Deino- 
therium,  the  equally  extinct  Mastodons,  and  the  Elephants;  and 
all  these  three  types  are  known  to  have  been  in  existence  as 
early  as  the  Miocene  period,  the  first  of  them  being  exclusively 
confined  to  deposits  of  this  age.  Of  the  three,  the  genus 
Deincthcrium  is  much  the  most  abnormal  in  its  characters; 
so  much  so,  that  good  authorities  regard  it  as  being  one 
of  the  Sea-cows  (Sirenia) — though  this  view  has  been  rendered 
untenable  by  the  discovery  of  limb-bones  which  can  hardly 
belong  to  any  other  animal,  and  which  are  distinctly  Probosci- 
dean in  type.  The  most  celebrated  skull  of  the  Deinothere 
(fig.  246)  is  one  which  was  exhumed  from  the  Upper  Miocene 
deposits  of  Epplesheim,  in  Hesse- 
Darmstadt,  in  the  year  1836. 
This  skull  was  four  and  a  half 
feet  in  length,  and  indicated  an 
animal  larger  than  any  existing 
species  of  Elephant.  The  upper 
jaw  is  destitute  of  incisor  or 
canine  teeth,  but  is  furnished  on 
each  side  with  five  molars,  which 
are  opposed  to  a  corresponding 
series  of  grinding  teeth  in  the 
lower  jaw.  No  canines  are  pres- 
ent in  the  lower  jaw;  but  the 
front  portion  of  the  jaw  is  ab- 
ruptly bent  downwards,  and  car- 
ries two  huge  tusk-like  incisor 
teeth,  which  are  curved  down- 
wards and  backwards,  and  the  use  of  which  is  rather  problem- 
atical. Not  only  does  the  Deinothere  occur  in  Europe,  but 
remains  belonging  to  this  genus  have  also  been  detected  in  the 
Siwalik  Hills,  in  India. 

The  true  Elephants  (Elcphas}  do  not  appear  to  have  ex- 
isted during  the  Miocene  period  in  Europe,  but  several  species 
have  been  detected  in  the  Upper  Miocene  deposits  of  the 


Fig.  246  —Skull  of  Deinotherium 
gigdnteum,  greatly  reduced.  From 
the  Upper  Miocene  of  Germany. 


332 


HISTORICAL  PALAEONTOLOGY. 


Siwalik  Hills,  in  India.  The  fossil  forms,  though  in  all  cases 
specifically,  and  in  some  cases  even  sub-generically,  distinct, 
agree  with  those  now  in  existence  in  the  general  conformation 
of  their  skeleton,  and  in  the  principal  characters  of  their  den- 
tition. In  all,  the  canine  teeth  are  wanting  in  both  jaws;  and 
there  are  no  incisor  teeth  in  the  lower  jaw,  whilst  there  are 
two  incisors  in  the  front  of  the  upper  jaw,  which  are  de- 
veloped into  two  huge  "  tusks. "  There  are  six  molar  teeth 
on  each  side  of  both  the  upper  and  lower  jaw,  but  only 


B 


Fig.  247. — A,  Molar  tooth  of  Elephas  planifrons,  one-third  of  the  natural  size,  show- 
ing the  grinding  surface — from  the  Upper  Miocene  of  India  ;  B.  Profile  view  of  the 
last  upper  inolar  of  .Mastodon  Sivalensis,  one-third  of  the  natural  size — from  the  Upper 
Miocene  of  India.  (After  Falconer.) 

one,  or  at  most  a  part  of  two,  is  in  actual  use  at  any  given 
time;  and  as  this  becomes  worn  away,  it  is  pushed  forward 
and  replaced  by  its  successor  behind  it.  The  molars  are  of 
very  large  size,  and  are  each  composed  of  a  number  of  trans- 


THE  MIOCENE  PERIOD.  333 

verse  plates  of  enamel  united  together  by  ivory ;  and  by  the 
process  of  mastication,  the  teeth  become  worn  down  to  a  flat 
surface,  crossed  by  the  enamel-ridges  in  varying  patterns. 
These  patterns  are  different  in  the  different  species  of  Ele- 
phants, though  constant  for  each;  and  they  constitute  one  of 
the  most  readily  available  means  of  separating  the  fossil 
forms  from  one  another.  Of  the  seven  Miocene  Elephants 
of  India,  as  judged  by  the  characters  of  the  molar  teeth, 
two  are  allied  to  the  existing  Indian  Elephant,  one  is  related 
to  the  living  African  Elephant,  and  the  remaining  four  are  in 
some  respects  intermediate  between  the  true  Elephants  and 
the  Mastodons. 

The  Mastodons,  lastly,  though  quite  elephantine  in  their 
general  characters,  possess  molar  teeth  which  have  their  crowns 
furnished  with  conical  eminences  or  tubercles  placed  in  pairs 
(fig.  247,  B),  instead  of  having  the  approximately  flat  surface 
characteristic  of  the  grinders  of  the  Elephants.  As  in  the 
latter,  there  are  two  upper  incisor  teeth,  which  grow  perma- 
nently during  the  life  of  the  animal,  and  which  constitute  great 
tusks;  but  the  Mastodons,  in  addition,  o'ften  possess  two  lower 
incisors,  which  in  some  cases  likewise  grow  into  small  tusks. 
Three  species  of  Mastodon  are  known  to  occur  in  the  Upper 
Miocene  of  the  Siwalik  Hills  of  India;  and  the  Miocene  de- 
posits of  the  European  area  have  yielded  the  remains  of  four 
species,  of  which  the  best  known  are  the  M.  longirostris  and  the 
M.  angustidens. 

Whilst  herbivorous  Quadrupeds,  as  we  have  seen,  were 
extremely  abundant  during  Miocene  times,  and  often  attained 
gigantic  dimensions,  Beasts  of  Prey  (Carnivora)  were  by  no 
means  wanting,  most  of  the  principal  existing  families  of  the 
order  being  represented  in  deposits  of  this  age.  Thus,  we  find 
aquatic  Carnivores  belonging  to  both  the  living  groups  of  the 
Seals  and  Walruses;  true  Bears  are  wanting,  but  their  place 
is  filled  by  the  closely-allied  genus  Amphicyon,  of  which  various 
species  are  known;  Weasels  and  Otters  were  not  unknown, 
and  the  Hycunictis  and  Ictitherium  of  the  Upper  Miocene  of 
Greece  are  apparently  intermediate  between  the  Civet-cats  and 
the  Hyaenas;  whilst  the  great  Cats  of  subsequent  periods  are 
more  than  adequately  represented  by  the  huge  "  Sabre-toothed 
Tiger"  (Machairodus),  with  its  immense  trenchant  and  serrated 
canine  teeth. 

Amongst  the  Rodent  Mammals,  the  Miocene  rocks  have 
yielded  remains  of  Rabbits,  Porcupines  (such  as  the  Hystrix 


334  HISTORICAL  PALAEONTOLOGY. 

primigenius  of  Greece),  Beavers,  Mice,  Jerboas,  Squirrels,  and 
Marmots.  All  the  principal  living  groups  of  this  order  were 
therefore  differentiated  in  Middle  Tertiary  times. 

The  Cheiroptera  are  represented  by  small  insect-eating  Bats ; 
and  the  order  of  the  Insectivorous  Mammals  is  represented  by 
Moles,  Shrew-mice,  and  Hedgehogs. 

Lastly,  the  Monkeys  (Quadrumana)  appear  to  have  existed 
during  the  Miocene  period  under  a  variety  of  forms,  remains 
of  these  animals  having  been  found  both  in  Europe  and  in 
India;  but  no  member  of  this  order  has  as  yet  been  detected 
in  the  Miocene  Tertiary  of  the  North  American  continent. 
Amongst  the  Old  World  Monkeys  of  the  Miocene,  the  two 
most  interesting  are  the  PliopitJiecus  and  Dryopithecus  of  France. 


Fig.  248.— Lower  jaw  of  Pliapitliecus  antiquus.    Upper  Miocene,  France. 

The  former  of  these  (fig.  248)  is  supposed  to  have  been  most 
nearly  related  to  the  living  Semno  pithed  of  Southern  Asia,  in 
which  case  it  must  have  possessed  a  long  tail.  The  Mesopi- 
thecus  of  the  Upper  Miocene  of  Greece  is  also  one  of  the  lower 
Monkeys,  as  it  is  most  closely  allied  to  the  existing  Macaques. 
On  the  other  hand,  the  Dryopithecus  of  the  French  Upper 
Miocene  is  referable  to  the  group  of  the  "  Anthropoid  Apes, " 
and  is  most  nearly  related  to  the  Gibbons  of  the  present  day, 
in  which  the  tail  is  rudimentary  and  there  are  no  cheek- 
pouches.  Dryopithecus  was,  also,  of  large  size,  equalling  Man 
in  stature,  and  apparently  living  amongst  the  trees  and  feed- 
ing upon  fruits. 


THE  PLIOCENE  PERIOD.  335 


CHAPTER  XX. 
THE  PLIOCENE  PERIOD. 

The  highest  division  of  the  Tertiary  deposits  is  termed  the 
Pliocene  formation,  in  accordance  with  the  classification  pro- 
posed by  Sir  Charles  Lyell.  The  Pliocene  formations  contain 
from  45  to  95  per  cent  of  existing  species  of  Mollusca,  the  re- 
mainder belonging  to  extinct  species.  They  are  divided  by  Sir 
Charles  Lyell  into  two  divisions,  the  Older  Pliocene  and  Newer 
Pliocene. 

The  Pliocene  deposits  of  Britain  occur  in  Suffolk,  and  are 
known  by  the  name  of  "  Crags,"  this  being  a  local  term  used 
for  certain  shelly  sands,  which  are  employed  in  agriculture. 
Two  of  these  Crags  are  referable  to  the  Older  Pliocene,  viz., 
the  White  and  Red  Crags, — and  one  belongs  to  the  Newer 
Pliocene,  viz.,  the  Norwich  Crag. 

The  White  or  Coralline  Crag  of  Suffolk  is  the  oldest  of  the 
Pliocene  deposits  of  Britain,  and  is  an  exceedingly  local  for- 
mation occurring  in  but  a  single  small  area,  and  having  a 
maximum  thickness  of  not  more  than  50  feet.  It  consists  of 
soft  sands,  with  occasional  intercalations  of  flaggy  limestone. 
Though  of  small  extent  and  thickness,  the  Coralline  Crag  is  of 
importance  from  the  number  of  fossils  which  it  contains.  The 
name  "  Coralline "  is  a  misnomer ;  since  there  are  few  true 
Corals,  and  the  so-called  "  Corals  "  of  the  formation  are  really 
Polyzoa,  often  of  very  singular  forms.  The  shells  of  the  Coral- 
line Crag  are  mostly  such  as  inhabit  the  seas  of  temperate 
regions;  but  there  occur  some  forms  usually  looked  upon  as 
indicating  a  warm  climate. 

The  Upper  or  Red  Crag  of  Suffolk — like  the  Coralline  Crag 
— has  a  limited  geographical  extent  and  a  small  thickness, 
rarely  exceeding  40  feet.  It  consists  of  quartzose  sands,  usu- 
ally deep  red  or  brown  in  color,  and  charged  with  numerous 
fossils. 

Altogether  more  than  200  species  of  shells  are  known  from 
the  Red  Crag,  of  which  60  per  cent  are  referable  to  existing 


336  HISTORICAL  PALEONTOLOGY. 

species.  The  shells  indicate,  upon  the  whole,  a  temperate  or 
even  cold  climate,  decidedly  less  warm  than  that  indicated  by 
the  organic  remains  of  the  Coralline  Crag.  It  appears,  there- 
fore, that  a  gradual  refrigeration  was  going  on  during  the 
Pliocene  period,  commencing  in  the  Coralline  Crag,  becoming 
intensified  in  the  Red  Crag,  being  still  more  severe  in  the 
Norwich  Crag,  and  finally  culminating  in  the  Arctic  cold  of  the 
Glacial  period. 

Besides  the  Mollusca,  the  Red  Crag  contains  the  ear-bones 
of  Whales,  the  teeth  of  Sharks  and  Rays,  and  remains  of  the 
Mastodon,  Rhinoceros,  and  Tapir. 

The  Newer  Pliocene  deposits  are  represented  in  Britain  by 
the  Norwich  Crag,  a  local  formation  occurring  near  Norwich. 
It  consists  of  incoherent  sands,  loams,  and  gravels,  resting  in 
detached  patches,  from  2  to  20  feet  in  thickness,  upon  an 
eroded  surface  of  Chalk.  The  Norwich  Crag  contains  a  mix- 
ture of  marine,  land,  and  fresh-water  shells,  with  remains  of 
fishes  and  bones  of  mammals;  so  that  it  must  have  been  de- 
posited at  a  local  sea-deposit  near  the  mouth  of  an  ancient 
river.  It  contains  altogether  more  than  100  marine  shells, 
of  which  89  per  cent  belong  to  existing  species.  Of  the 
Mammals,  the  two  most  important  are  an  Elephant  (Elefihas 
meridionalis),  and  the  characteristic  Pliocene  Mastodon  (M. 
Arvernensis} ,  which  is  hitherto  the  only  Mastodon  found  in 
Britain. 

According  to  the  most  recent  views  of  high  authorities, 
certain  deposits — such  as  the  so-called  "  Bridlington  Crag "  of 
Yorkshire,  and  the  "  Chillesford  beds "  of  Suffolk — are  to  be 
also  included  in  the  Newer  Pliocene,  upon  the  ground  that 
they  contain  a  small  proportion  of  extinct  shells.  Our  knowl- 
edge, however,  of  the  existing  Molluscan  fauna,,  is  still  so  far 
incomplete,  that  it  may  reasonably  be  doubted  if  these  sup- 
posed extinct  forms  have  actually  made  their  final  disappear- 
ance, whilst  the  strata  in  question  have  a  strong  natural  con- 
nection with  the  "  Glacial  deposits,"  as  shown  by  the  number 
of  Arctic  Mollusca  which  they  contain.  Here,  therefore,  these 
beds  will  be  included  in  the  Post-Pliocene  series,  in  spite  of 
the  fact  that  some  of  their  species  of  shells  are  not  known  to 
exist  at  the  present  day. 

The  following  are  the  more  important  Pliocene  deposits 
which  have  been  hitherto  recognized  out  of  Britain  : — 

I.  In  the  neighborhood  of  Antwerp  occur  certain  "crags," 


THE  PLIOCENE  PERIOD.  3S7 

which  are  the  equivalent  of  the  White  and  Red  Crag  in  part. 
The  lowest  of  these  contains  less  than  50  per  cent,  and  the 
highest  60  per  cent,  of  existing  species  of  shells,  the  remainder 
being  extinct. 

2.  Bordering  the  chain  of  the  Apennines,  in   Italy,  on  both 
sides  is  a  series  of  low  hills  made  up  of  Tertiary  strata,  which 
are    known    as    the    Sub-Apennine    beds.      Part    of    these    is    of 
Miocene   age,   part   is   Older   Pliocene,   and   a  portion   is    Newer 
Pliocene.      The    Older    Pliocene    portion    of    the    Sub-Apennines 
consists    of    blue    or    brown    marls,    which    sometimes    attain    a 
thickness  of  2000  feet. 

3.  In    the    valley    of    the    Arno,    above    Florence,    are    both 
Older  and  Newer  Pliocene  strata.     The  former  consist  of  blue 
clays    and    lignites,    with    an    abundance    of    plants.      The    latter 
consist  of  sands  and  conglomerates,  with  remains  of  large  Car- 
nivorous   Mammals,    Mastodon,    Elephant,    Rhinoceros,    Hippo- 
potamus, &c.' 

4.  In  Sicily,  Newer  Pliocene  strata  are  probably  more  largely 
developed   than    anywhere    else   in   the   world,    rising   sometimes 
to   a   height   of   3000    feet   above   the    sea.      The    series    consists 
of   clays,   marls,    sands,    and   conglomerates,   capped   by   a   com- 
pact  limestone,   which   attains   a   thickness   of    from    700   to   800 
feet.     The  fossils  of  these  beds  belong  almost  entirely  to  living 
species,   one  of  the  commonest  being  the   Great   Scallop   of   the 
Mediterranean  (Pecten  Jacobaus). 

5.  Occupying    an    extensive    area    round    the    Caspian,    Aral, 
and    Azof    Seas,    are    Pliocene    deposits   known    as    the    "  Aralo- 
Caspian "    beds.      The    fossils    in    these    beds    are    partly    fresh- 
water, partly  marine,  and  partly  intermediate  in  character,   and 
they    are    in    great    part    identical    with   -species    now    inhabiting 
the    Caspian.      The    entire    formation    appears    to    indicate    the 
former  existence  of  a  great  sheet  of  brackish  water,  forming  an 
inland  sea,  like  the  Caspian,  but  as  large  as,  or  larger  than,  the 
Mediterranean. 

6.  In  the  United  States,  strata  of  Pliocene  age  are  found  in 
North  and   South   Carolina.     They  consist  of   sands   and  clays, 
with     numerous     fossils,     chiefly     Molluscs     and     Echinoderms. 
From    40    to    60    per    cent    of    the    fossils    belong    to    existing 
species.     On  the  Loup   Fork  of  the  river   Platte,   in   the  Upper 
Missouri  region,  are  strata  which  are  also  believed  to  be  refer- 
able to  the  Pliocene  period,  and  probably  to  its  upper  division. 
They   are   from   300  to  400   feet  thick,   and  contain   land-shells, 

22 


338  HISTORICAL  PALEONTOLOGY. 

with  the  bones  of  numerous  Mammals,  such  as  Camels,  Rhino- 
ceroses, Mastodons,  Elephants,  the  Horse,  Stag,  &c. 

As  regards  the  life  of  the  Pliocene  period,  there  are  only 
two  classes  of  organisms  to  which  our  attention  need  he 
directed — namely,  the  Shell-fish  and  the  Mammals.  So  far  as 
the  former  are  concerned,  we  have  to  note  in  the  first  place 
that  the  introduction  of  new  species  of  animals  upon  the  globe 
went  on  rapidly  during  this  period.  In  the  Older  Pliocene 
deposits,  the  number  of  shells  of  existing  species  is  only  from 
40  to  60  per  cent;  but  in  the  Newer  Pliocene  the  pro- 
portion of  living  forms  rises  to  as  much  as  from  80  to 
95  per  cent.  Whilst  the  Molluscs  thus  become  rapidly  mod- 
ernized, the  Mammals  still  all  belong  to  extinct  species, 
though  modern  generic  types  gradually  supersede  the  more 
antiquated  forms  of  the  Miocene.  In  the  second  place,  there 
is  good  evidence  to  show  that  the  Pliocene  period  was  one  in 
which  the  climate  of  the  northern  hemisphere  underwent  a 
gradual  refrigeration.  In  the  Miocene  period,  there  is  evi- 
dence to  show  that  Europe  possessed  a  climate  very  similar 
to  that  now  enjoyed  by  the  Southern  United  States,  and  cer- 
tainly very  much  warmer  than  it  is  at  present.  The  presence 
of  Palm-trees  upon  the  land,  and  of  numerous  large  Cowries, 
Cones,  and  other  shells  of  warmer  regions  in  the  sea,  sufficiently 
proves  this.  In  the  Older  Pliocene  deposits,  on  the  other 
hand,  northern  forms  predominate  amongst  the  Shells,  though 
some  of  the  types  of  hotter  regions  still  survive.  In  the  Newer 
Pliocene,  again,  the  Molluscs  are  such  as  almost  exclusively 
inhabit  the  seas  of  temperate  or  even  cold  regions ;  whilst  if 
we  regard  deposits  like  the  "  Bridlington  Crag "  and  "  Chilles- 
ford  beds "  as  truly  referable  to  this  period,  we  meet  at  the 
close  of  this  period  with  shells  such  as  nowadays  are  distinct- 
ively characteristic  of  high  latitudes.  It  might  be  thought 
that  the  occurrence  of  Quadrupeds  such  as  the  Elephant, 
Rhinoceros,  and  Hippopotamus,  would  militate  against  this 
generalization,  and  would  rather  support  the  view  that  the 
climate  of  Europe  and  the  United  States  must  have  been  a 
hot  one  during  the  later  portion  of  the  Pliocene  period.  We 
have,  however,  reason  to  believe  that  many  of  these  extinct 
Mammals  were  more  abundantly  furnished  with  hair,  and  more 
adapted  to  withstand  a  cool  temperature,  than  any  of  their 
living  congeners.  We  have  also  to  recollect  that  many  of 
these  large  herbivorous  quadrupeds  may  have  been,  and 
indeed  probably  were,  more  or  less  migratory  in  their  habits; 


THE  PLIOCENE  PERIOD. 


339 


and  that  whilst  the  winters  of  the  later  portion  of  the  Pliocene 
period  were  cold,  the  summers  might  have  been  very  hot. 
This  would  allow  of  a  northward  migration  of  such  terrestrial 
animals  during  the  summer-time,  when  there  would  be  "an 
ample  supply  of  food  and  a  suitably  high  temperature,  and  a 
southward  recession  towards  the  approach  of  winter. 

The  chief  palaeontological  interests  of  the  Pliocene  deposits, 
as  of  the  succeeding  Post- Pliocene,  center  round  the  Mammals 
of  the  period ;  and  amongst  the  many  forms  of  these  we  may 
restrict  our  attention  to  the  orders  of  the  Hoofed  Quadrupeds 
(Ungulates),  the  Proboscideans,  the  Carnivora,  and  the  Quad- 
rumana.  Almost  all  the  other  Mammalian  orders  are  more 


Fig.  249  — A,  Under  surface  of  the  skull  of  Rhinoceros  Etruscus,  one-seventh  of 
the  natural  size — Pliocene,  Italy  ;  B.  Crowns  of  the  three  true  molars  of  the  upper 
jaw,  left  side,  of  Rhinoceros  meaarJiinHs  (R.  leptorhinun,  Falconer),  one-half  of  the 
natural  size— Pliocene,  France.  (After  Falconer.) 

or   less   fully  represented  in   Pliocene   times,   but  none   of   them 
attains  any  special  interest  till  we  enter  upon  the  Post-Pliocene. 


340  HISTORICAL  PALEONTOLOGY. 

Amongst  the  Odd-toed  Ungulates,  in  addition  to  the  remains 
of  true  Tapirs  (Tapirus  Arvernensis} ,  we  meet  with  the  bones 
of  several  species  of  Rhinoceros,  of  which  the  Rhinoceros  Etrus- 
cus  and  R.  megarhinus  (fig.  249)  are  the  most  important.  The 
former  of  these  (fig.  249,  A)  derives  its  specific  name  from  its 
abundance1  in  the  Pliocene  deposits  of  the  Val  d'Arno,  near 
Florence,  and  though  principally  Pliocene  in  its  distribution, 
it  survived  into  the  earlier  portion  of  the  Post-Pliocene  period. 
Rhinoceros  Etruscus  agreed  with  the  existing  African  forms  in 
having  two  horns  placed  one  behind  the  other,  the  front  one 
being  the  longest ;  but  it  was  comparatively  slight  and  slender 
in  its  build,  whilst  the  nostrils  were  separated  by  an  incom- 
plete bony  partition.  In  the  Rhinoceros  megarhinus  (fig.  249, 
B),  on  the  other  hand,  no  such  partition  exists  between  the 
nostrils,  and  the  nasal  bones  are  greatly  developed  in  size.  It 
was  a  two-horned  form,  and  is  found  associated  with  Elephas 
meridionalis  and  E.  antiquus  in  the  Pliocene  deposits  of  the 
Val  d'Arno,  near,  Florence.  Like  the  preceding,  it  survived, 
in  diminished  numbers,  into  the  earlier  portion  of  the  Post- 
Pliocene  period. 

The  Horses  (Equidcz)  are  represented,  both  in  Europe  and 
America,  by  the  three-toed  Hipparions,  which  survive  from  the 
Miocene,  but  are  now  verging  upon  extinction.  For  the  first 
time,  also,  we  meet  with  genuine  Horses  (Equus),  in  which 
each  foot  is  provided  with  a  single  complete  toe  only,  encased 
in  a  single  broad  hoof.  One  of  the  American  species  of  this 
period  (the  Equus  excelsus)  quite  equalled  the  modern  Horse 
in  stature ;  and  it  is  interesting  to  note  the  occurrence  of  indig- 
enous horses  in  America  at  such  a  comparatively  late  geo- 
logical epoch,  seeing  that  this  continent  certainly  possessed 
none  of  these  animals  when  first  discovered  by  the  Spaniards. 

Amongst  the  Even-toed  Ungulates,  we  may  note  the  occur- 
rence of  Swine  (Suida),  of  forms  allied  to  the  Camels  (Camel- 
ides),  and  of  various  kinds  of  Deer  (Cervidce)  ;  but  the  most 
interesting  Pliocene  Mammals  belonging  to  this  section  is  the 
great  Hippopotamus  major  of  Britain  and  Europe.  This  well- 
known  species  is  very  closely  allied  to  the  living  Hippopotamus 
amphibius  of  Africa,  from  which  it  is  separated  only  by  its 
larger  dimensions,  and  by  certain  points  connected  with  the 
conformation  of  the  skeleton.  It  is  found  very  abundantly  in 
the  Pliocene  deposits  of  Italy  and  France,  associated  with  the 
remains  of  the  Elephant,  Mastodon,  and  Rhinoceros,  and  it 
siirvived  into  the  earlier  portion  of  the  Post-Pliocene  period. 


THE  PLIOCENE  PERIOD.  341 

During  this  last-mentioned  period,  it  extended  its  range  north- 
wards, and  is  found  associated  with  the  Reindeer,  the  Bison, 
and  other  northern  animals.  From  this  fact  it  has  been  in- 
ferred, with  great  probability,  that  the  Hippopotamus  major  was 
furnished  with  a  long  coat  of  hair  and  fur,  thus  differing  from 
its  nearly  hairless  modern  representative,  and  resembling  its 
associates,  the  Mammoth  and  the  Woolly  Rhinoceros. 

Passing  on  to  the  Pliocene  Proboscideans,  we  find  that  the 
great  Deinotheria  of  the  Miocene  have  now  wholly  disappeared, 
and  the  sole  representatives  of  the  order  are  Mastodons  and 
Elephants.  The  most  important  member  of  the  former  group 
is  the  Mastodon  Arvernensis  (fig.  250),  which  ranged  widely 
over  Southern  Europe  and  England,  being  generally  associated 
with  remains  of  the  Eleplias  mcridionalis,  E.  antiquus,  Rhino- 
ceros megarhinus,  and  Hippopotamus  major.  The  lower  jaw 


Fig.  250. — Third  mllk-rnolar  of  the  left  side  of  the  upper  jaw  of  Mastodon 
Arvernensis,  showing  the  grinding  surface.    Pliocene. 

seems  to  have  been  destitute  of  incisor  teeth ;  but  the  upper 
incisors  are  developed  into  great  tusks,  which  sometimes  reach 
a  length  of  nine  feet,  and  which  have  the  simple  curvature  of 
the  tusks  of  the  existing  Elephants.  Amongst  the  Pliocene 
Elephants  the  two  most  important  are  the  Elephas  meridionalis 
and  the  Elephas  antiquus.  Of  these,  the  Elephas  meridionalis 
(fig.  251)  is  found  abundantly  in  the  Pliocene  deposits  of 
Southern  Europe  and  England,  and  also  survived  into  the 
•earlier  portion  of  the  Post-Pliocene  period.  Its  molar  teeth 
are  of  the  type  of  those  of  the  existing  African  Elephant,  the 
spaces  enclosed  by  the  transverse  enamel-plates  being  more 


342  HISTORICAL  PALEONTOLOGY. 

or  less  lozenge-shaped,  whilst  the  curvature  of  the  tusks  is 
simple.  The  Elephas  antiquus  (fig.  252)  is  very  generally 
associated  with  the  preceding,  and  it  survived  to  an  even 
later  stage  of  the  Post-Pliocene  period.  The  molar  teeth  are 
of  the  type  of  the  existing  Indian  Elephant,  with  compara- 
tively thin  enamel-ridges,  placed  closer  together  than  in  the 
African  type ;  whilst  the  tusks  were  nearly  straight. 


Tig.  251.— Molar  tooth  of  Elepha.8  meridionalis,  one-third  of  the  natural  size. 
Pliocene  and  Post-Pliocene. 


Amongst  the  Pliocene  Carnivores,  we  meet  with  true  Bears 
(Ursus  Arvernensis),  Hyaenas  (such  as  Hyccna  Hipparionum), 
and  genuine  Lions  (such  as  the  Felis  augustus  of  North 
America)  ;  but  the  most  remarkable  of  the  beasts  of  prey  of 
this  period  is  the  great  "Sabre-toothed  Tiger"  (Machairodus), 


Fig.  252.— Molar  tooth  of  Elephas  antiquus,  one-third  of  the  natural  size. 
Pliocene  and  Post-Pliocene. 


species  of  which  existed  in  the  earlier  Miocene,  and  survived 
to  the  later  Post-Pliocene.  In  this  remarkable  form  we  are 
presented  with  perhaps  the  most  highly  carnivorous  type  of 


THE  PLIOCENE  PERIOD. 


343 


all  known  beasts  of  prey.  Xot  only  are  the  jaws  shorter  in 
proportion  even  than  those  of  the  great  Cats  of  the  present 
clay,  but  the  canine  teeth  (fig.  253)  are  of  enormous  size, 
greatly  flattened  so  as  to  assume  the  form  of  a  poignard,  and 


Fig.  25:5.— A.  Skull  of  Mitclinirodua   cultridens.  without  the  lower  jaw.   reduced   In 
size  ;  B,  Canine  tooth  of  the  same,  one-half  the  natural  size.    Pliocene,  France. 


having  their  margins  finely  serrated.  Apart  from  the  charac- 
ters of  the  skull,  the  remainder  of  the  skeleton,  so  far  as  known, 
exhibits  proofs  that  the  Sabre-toothed  Tiger  was  extraordi- 
narily muscular  and  powerful,  and  in  the  highest  degree  adapt- 
ed for  a  life  of  rapine.  Species  of  Machairodus  must  have 
been  as  large  as  the  existing  Lion  ;  and  the  genus  is  not  only 
European,  but  is  represented  both  in  South  America  and  in 
India,  so  that  the  geographical  range  of  these  predaceous 
beasts  must  have  been  very  extensive. 

Lastly,  we  may  note  that  Pliocene  deposits  of  Europe 
have  yielded  the  remains  of  Monkeys  (Quadrumana) ,  allied  to 
the  existing'  Semnopitheci  and  Macaques. 


344  HISTORICAL  PALEONTOLOGY. 

LITERATURE. 

The  following  list  comprises  a  small  selection  of  some  of  the 
more  important  and  readily  accessible  works  and  memoirs 
relating  to  the  Tertiary  rocks  and  their  fossils.  With  few  ex- 
ceptions, foreign  works  relating  to  the  Tertiary  strata  of  the 
continent  of  Europe  or  their  organic  remains  have  been 
omitted : — 

(1)  'Elements  of  Geology.'     Lyell. 

(2)  '  Students'  Elements  of  Geology. '     Lyell. 

(3)  'Manual  of   Palaeontology.'     Owen. 

(4)  '  British  Fossil   Mammals  and  Birds. '     Owen. 

(5)  '  Traite  de  Paleontologie. '     Pictet. 

(6)  '  Cours   Elementaire   de   Paleontologie. '   D'Orbigny. 

(7)  "Probable    Age    of    the    London    Clay,"    &c. — 'Quart. 
Journ.  Geol.  Soc., '  vol.  iii.     Prestwich. 

(8)  '  Structure  and  Probable  Age  of  the  Bagshot  Sands ' — 

Ibid.,  vol.  iii.   Prestwich. 

(9)  '  Tertiary    Formations    of    the    Isle    of    Wight ' — Ibid., 

vol.  ii.  Prestwich. 
(10)   '  Structure  of  the  Strata  between  the  London  Clay  and 

the  Chalk, '  &c. — Ibid.,  vols.  vi.,  viii.,  and  x.  Prestwich. 
(n)   'Correlation    of    the    Eocene    Tertiaries    of    England, 

France,    and    Belgium' — Ibid,,    vol.    xxvii.      Prestwich. 

(12)  'On    the    Fluvio-marine    Formations    of    the    Isle    of 

Wight' — Ibid.,  vol.  ix.     Edward  Forbes. 

(13)  'Newer  Tertiary  Deposits  of  the  Sussex  Coast' — Ibid., 

vol.  xiii.  Godwin-Austen. 

(14)  'Kainozoic   Formations   of    Belgium' — Ibid.,   vol.    xxii. 

Godwin-Austen. 

(15)  'Tertiary   Strata  of   Belgium  and  French  Flanders' — 

Ibid.,  vol.  viii.     Lyell. 

(16)  'On    Tertiary   Leaf-beds    in   the    Isle    ©f    Mull'— Ibid., 

vol.  vii.     The  Duke  of  Argyll. 

(17)  'Newer  Tertiaries  of  Suffolk  and  their  Fauna' — Ibid., 

vol.  xxvi.     Ray  Lankester. 

(18)  'Lower  London   Tertiaries   of   Kent' — Ibid.,  vol.   xxii. 

AVhitaker. 

(19)  "Guide    to    the    Geology    of    London" — 'Mem.    Geol. 

Survey. '     Whitaker. 

(20)  'Memoirs  of  the  Geological  Survey  of  Great  Britain.' 

(21)  'Introductory    Outline    of    the    Geology    of    the    Crag 

District'  (Supplement    to    Crag    Mollusca,    Palseonto- 

graphical  Society).  S.  V.  Wood,  jun.,  and  F.  W. 
Harmer. 

(22)  "  Tertiary  Fluvio-marine     Deposits     of     the     Isle     of 

Wight. "  Edward  Forbes.  Edited  by  Godwin- 
Austen  ;  with  Descriptions  of  the  Fossils  by  Morris, 
Salter,  and  Rupert  Jones — '  Memoirs  of  the  Geo- 
logical Survey.' 

(23)  '  Geological    Excursions    round    the    Isle    of    Wight. ' 

Mantell. 

(24)  '  Catalogue  of  British  Fossils. '    Morris, 


THE  PLIOCENE  PERIOD.  345 

(25)  '  Catalogue    of    Fossils    in    the    Museum    of    Practical 

Geology.'    Etheridge. 

(26)  'Monograph  of  the  Crag  Polyzoa '  (  Palaeontographical 

Society).     Busk. 

(27)  'Monograph    of    the    Tertiary    Brachiopoda '     (Ibid.) 

Davidson. 

(28)  '  Monograph    of  the    Tertiary    Malacostracous    Crus- 

tacea'  (Ibid.)     Bell. 

(29)  'Monograph  of  the  Tertiary  Corals'    (Ibid.)     Milne- 
Edwards  and  Haime. 

(30)  'Supplement  to  the  Tertiary  Corals'    (Ibid.)      Martin 

Duncan. 

(31)  'Monograph  of  the  Eocene  Mollusca '    (Ibid.)      Fred. 

E.   Edwards. 

(32)  'Monograph  of  the  Eocene  Mollusca'  (Ibid.)     Searles 

V.  Wood. 

(33)  'Monograph  of  the   Crag  Mollusca'    (Ibid.)      Searles 

V.  Wood. 

(34)  'Monograph    of    the    Tertiary    Entomostraca '    (Ibid.) 

Rupert  Jones. 

(35)  'Monograph  of  the  Foraminifera  of  the  Crag'  (Ibid.) 

Rupert  Jones,  Parker,  and  H.  B.  Brady. 

(36)  '  Monograph    of    the    Radiaria    of    the    London    Clay ' 

(Ibid.)     Edward  Forbes. 

(37)  'Monograph  of  the  Cetace'a  of  the  Red  Crag'   (Ibid.) 

Owen. 

(38)  '  Monograph    of    the    Fossil    Reptiles    of    the    London 

Clay'   (Ibid.)     Owen  and  Bell. 

(39)  "  On  the  Skull  of  a  Dentigerous  Bird  from  the  Lon- 

don   Clay   of    Sheppey " — '  Quart.    Journ.    Geol.    Soc.,' 
vol.  xxix.    Owen. 

(40)  'Ossemens  Fossiles.'     Cuyier. 

(41)  'Fauna  Antiqua  Sivalensis. '     Falconer  and  Sir  Proby 

Cautley. 

(42)  '  Palreontological  Memoirs. '     Falconer. 

(43)  '  Animaux  Fossiles  et  Geologic  de  1'Attique. '     Gaudry. 

(44)  "  Principal  Characters  of  the  Dinocerata  " — '  American 

Journ.  of  Science  and  Arts, '  vol.  xi.     Marsh. 

(45)  'Principal    Characters    of   the    Brontotheridae '    (Ibid.) 

Marsh. 

(46)  'Principal     Characters     of     the     Tillodontia '     (Ibid.) 

Marsh. 

(47)  "Extinct   Vertebrata   of   the    Eocene   of   Wyoming" — 

'Geological  Survey  of  Montana,'  &c.,  1872.     Cope. 

(48)  "  Ancient    Fauna    of    Nebraska " — '  Smithsonian    Con- 

tributions to  Knowledge, '  vol.  vi.  Leidy. 

(49)  '  Manual  of  Geology. '     Dana. 

(50)  "  Palaeontology  and  Evolution  "  .(Presidential  Address 

to  the  Geological  Society  of  London,  1870) — 'Quart. 
Journ.  Geol.  Soc., '  vol.  xxvi.     Huxley. 

(51)  'Mineral  Conchology. '     Sowerby. 

(52)  '  Description  des  Coquilles  Fossiles,'  &c.     Deshayes. 

(53)  '  Description    des    Coquilles    Tertiaries    de    Belgique.' 

(54)  '  Fossilen  Polypen  des  Wiener  Tertiar-beckens.'    Reuss, 


346  HISTORICAL  PALAEONTOLOGY. 

(55)  '  Palaeontologische    Studien    tiber    die    alteren    Tertiar- 

schichten  der  Alpen.'     Reuss. 

(56)  '  Land-    und    Siiss-wasser    Conchylien    der    Vorwelt.' 

Sandberger. 

(57)  '  Flora  Tertiaria  Helvetica. '    Heer. 

(58)  '  Flora  Fossilis  Arctica.'     Heer. 

(59)  '  Recherches   sur   le   Climat  et  la   Vegetation   du   Pays 

Tertiaire.'     Heer. 

(60)  I  Fossil  Flora  of  Great  Britain.'     Lindley  and  Hutton. 

(61)  'Fossil  Fruits  and  Seeds  of  the  London  Clay.'     Bower- 

bank. 

(62)  "  Tertiary  '  Leaf-beds    of    the    Isle    of    Mull"— '  Quart. 

Journ.  Geol.  Soc./  vol  vii.     Edward  Forbes. 

(63)  '  The    Geology    of    England    and    Wales.'      Horace    B. 

Woodward. 


CHAPTER  XXI. 

THE  QUATERNARY  PERIOD. 

THE  POST-PLIOCENE  PERIOD. 

Later  than  any  of  the  Tertiary  formations  are  various  de- 
tached and  more  or  less  superficial  accumulations,  which  are 
generally  spoken  of  as  the  Post-Tertiary  formations,  in  accord- 
ance with  the  nomenclature  of  Sir  Charles  Lyell — or  as  the 
Quaternary  formations,  in  accordance  with  the  general  usage 
of  Continental  geologists.  In  all  these  formations  we  meet 
with  no  Mollusca  except  such  as  are  now  alive — with  the 
partial  and  very  limited  exception  of  some  of  the  oldest  de- 
posits of  this  period,  in  which  a  few  of  the  shells  occasionally 
belong  to  the  species  not  known  to  be  in  existence  at  the  pres- 
ent day.  Whilst  the  Shell-fish  of  the  Quaternary  deposits  are, 
generally  speaking,  identical  with  existing  forms,  the  Mammals 
are  sometimes  referable  to  living,  sometimes  to  extinct  species. 
In  accordance  with  this,  the  Quaternary  formations  are  divided 
into  two  groups:  (i)  The  Post-Pliocene,  in  which  the  shells  are 
almost  invariably  referable  to  existing  species,  but  some  of  the 
Mammals  are  extinct;  and  (2)  the  Recent,  in  which  the  shells 
and  the  Mammals  alike  belong  to  existing  species.  The  Post- 
Pliocene  deposits  are  often  spoken  of  as  the  Pleistocene  forma- 
tions (Gr.  pleistos,  most;  kainos,  new  or  recent),  in  allusion  to 


THE  QUATERNARY  PERIOD.  347 

the  fact  that  the  great  majority  of  the  living  beings  of  this 
period  belong  to  the  species  characteristic  of  the  "  new "  or 
Recent  period. 

The  Recent  deposits,  though  of  the  highest  possible  interest, 
do  not  properly  concern  the  palaeontologist  strictly  so-called, 
but  the  zoologist,  since  they  contain  the  remains  of  none  but 
existing  animals.  They  are  "  Pre-historic,"  but  they  belong 
entirely  to  the  existing  terrestrial  order.  The  Post-Pliocene 
deposits,  on  the  other  hand,  contain  the  remains  of  various 
extinct  Mammals ;  and  though  Man  undoubtedly  existed  in, 
at  any  rate,  the  later  portion  of  this  period,  if  not  through- 
out the  whole  of  it,  they  properly  form  part  of  the  domain  of 
the  palaeontologist. 

The  Post-Pliocene  deposits  are  extremely  varied,  and  very 
widely  distributed  ;  and  owing  to  the  mode  of  their  occurrence, 
the  ordinary  geological  tests  of  age  are  in  their  case  but  very 
partially  available.  The  subject  of  the  classification  of  these 
deposits  is  therefore  an  extremely  complicated  one ;  and  as 
regards  the  age  of  even  some  of  the  most  important  of  them, 
there  still  exists  considerable  difference  of  opinion.  For  our 
present  purpose,  it  will  be  convenient  to  adopt  a  classifica- 
tion of  the  Post-Pliocene  deposits  founded  on  the  relations 
which  they  bear  in  time  to  the  great  "  Ice-age "  or  "  Glacial 
period;"  though  it  is  not  pretended  that  our  present  knowl- 
edge is  sufficient  to  render  such  a  classification  more  than  a 
provisional  one. 

In  the  early  Tertiary  period,  as  we  have  seen,  the  climate  of 
the  northern  hemisphere,  as  shown  by  the  Eocene  animals  and 
plants,  was  very  much  hotter  than  it  is  at  present — partaking, 
indeed,  of  a  sub-tropical  character.  In  the  Middle  Tertiary  or 
Miocene  period,  the  temperature,  though  not  so  high,  was  still 
much  warmer  than  that  now  enjoyed  by  the  northern  hemi- 
sphere ;  and  we  know  that  the  plants  of  temperate  regions  at 
this  time  flourished  within  the  Arctic  circle.  In  the  later 
Tertiary  or  Pliocene  period,  again,  there  is  evidence  that  the 
northern  hemisphere  underwent  a  further  progressive  diminu- 
tion of  temperature ;  though  the  climate  of  Europe  generally 
seems  at  the  close  of  the  Tertiary  period  to  have  been  if  any- 
thing warmer,  or  at  any  rate  not  colder,  than  it  is  at  the  present 
day.  With  the  commencement  of  the  Quaternary  period, 
however,  this  diminution  of  temperature  became  more  de- 
cided ;  and  beginning  with  a  temperate  climate,  we  find  the 
greater  portion  of  the  northern  hemisphere  to  become  gradu- 


348  HISTORICAL  PALAEONTOLOGY. 

ally  subjected  to  all  the  rigours  of  intense  Arctic  cold.  All 
the  mountainous  regions  of  Northern  and  Central  Europe,  of 
Britain,  and  of  North  America,  became  the  nurseries  of  huge 
ice-streams,  and  large  areas  of  the  land  appear  to  have  been 
covered  with  a  continuous  ice-sheet.  The  Arctic  conditions  of 
this,  the  well-known  "  Glacial  period,"  relaxed  more  than  once, 
and  were  more  than  once  re-established  with  lesser  intensity. 
Finally,  a  gradual  but  steadily  progressive  amelioration  of  tem- 
perature took  place;  the  ice  slowly  gave  way,  and  ultimately 
disappeared  altogether ;  and  the  climate  once  more  became 
temperate,  except  in  high  northern  latitudes. 

The  changes  of  temperature  sketched  out  above  took  place 
slowly  and  gradually,  and  occupied  the  whole  of  the  Post- 
Pliocene  period.  In  each  of  the  three  periods  marked  out  by 
these  changes — in  the  early  temperate,  the  central  cold,  and 
the  later  temperate  period — certain  deposits  were  laid  down 
over  the  surface  of  the  northern  hemisphere;  and  these  de- 
posits collectively  constitute  the  Post-Pliocene  formations. 
Hence  we  may  conveniently  classify  all  the  accumulations  of 
this  age  under  the  heads  of  (i)  Pre-Glacial  deposits,  (2)  Glacial 
deposits,  and  (3)  Post-Glacial  deposits,  according  as  they  were 
formed  before,  during,  or  after  the  "  Glacial  period."  It  can- 
not by  any  means  be  asserted  that  we  can  definitely  fix  the 
precise  relations  in  time  of  all  the  Post-Pliocene  deposits  to  the 
Glacial  period.  On  the  contrary,  there  are  some  which  hold  a 
very  disputed  position  as  regards  this  point;  and  there  are 
others  which  do  not  admit  of  definite  allocation  in  this  manner 
at  all,  in  consequence  of  their  occurrence  in  regions  where  no 
"  Glacial  Period "  is  known  to  have  been  established.  For 
our  present  purpose,  however,  dealing  as  we  shall  have  to  do 
principally  with  the  northern  hemisphere,  the  above  classifi- 
cation, with  all  its  defects,  has  greater  advantages  than  any 
other  that  has  been  yet  proposed. 

I.  PRE-GLACIAL  DEPOSITS. — The  chief  pre-glacial  deposit  of 
Britain  is  found  on  the  Norwalk  coast,  reposing  upon  the  Newer 
Pliocene  (Norwich  Crag),  and  consists  of  an  ancient  land-sur- 
face which  is  known  as  the  "  Cromer  Forest-bed." 

This  consists  of  an  ancient  soil,  having  embedded  in  it  the 
stumps  of  many  trees,  still  in  an  erect  position,  with  remains 
of  living  plants,  and  the  bones  of  recent  extinct  quadru- 
peds. It  is  overlaid  by  fresh-water  and  marine  beds,  all  the 
shells  of  which  belong  to  existing  species,  and  it  is  finally  sur- 


THE  QUATERNARY  PERIOD.  349 

mounted  by  true  "glacial  drift."  While  all  the  shells  and 
plants  of  the  Cromer  Forest-bed  and  its  associated  strata  belong 
to  existing  species,  the  Mammals  are  partly  living,  partly  ex- 
tinct. Thus  we  find  the  existing  Wolf  (Canis  lupus),  Red 
Deer  (Cervus  elaphus),  Roebuck  (Cervus  capreolus),  Mole 
(Talpa  Euro  pact),  and  Beaver  (Castor  fiber),  living  in  .western 
England  side  by  side  with  the  Hippopotamus  major,  Elephas 
antiquus,  Elephas  meridionalis,  Rhinoceros  Etruscus,  and  R. 
megarhinus  of  the  Pliocene  period,  which  are  not  only  extinct, 
but  imply  an  at  any  rate  moderately  warm  climate.  Besides 
the  above,  the  Forest-bed  has  yielded  the  remains  of  several 
extinct  species  of  Deer,  of  the  great  extinct  Beaver  (Trogon- 
therium  Cuvieri),  of  the  Caledonian  Bull  or  "  Urus "  (Bos 
priinigcnius) ,  and  of  a  Horse  (Equus  fossilis),  little  if  at  all 
distinguishable  from  the  existing  form. 

The  so-called  "  Bridlington  Crag "  of  Yorkshire,  and  the 
"  Chillesford  Beds  "  of  Suffolk,  are  probably  to  be  regarded  as 
also  belonging  to  this  period;  though  many  of  the  shells  which 
they  contain  are  of  an  Arctic  character,  and  would  indicate 
that  they  were  deposited  in  the  commencement  of  the  Glacial 
period  itself.  Owing,  however,  to  the  fact  that  a  few  of  the 
shells  of  these  deposits  are  known  to  occur  in  a  living  con- 
dition, these,  and  some  other  similar  accumulations,  are  some- 
times considered  as  referable  to  the  Pliocene  period. 

II.  GLACIAL  DEPOSITS. — Under  this  head  is  included  a 
great  series  of  deposits  which  are  widely  spread  over  both 
Europe  and  America,  and  which  were  formed  at  a  time  when 
the  climate  of  these  countries  was  very  much  colder  than  it  is 
at  present,  and  approached  more  or  less  closely  to  what  we  see 
at  the  present  day  in  the  Arctic  regions.  These  deposits  are 
known  by  the  general  name  of  the  Glacial  deposits,  or  by  the 
more  specialized  names  of  the  Drift,  the  Northern  Drift,  the 
Boulder-clay,  the  Till,  &c. 

These  glacial  deposits  are  found  in  Britain  as  far  south  as 
the  Thames,  over  the  whole  of  Northern  Europe,  in  all  the 
more  elevated  portions  of  Southern  and  Central  Europe,  and 
over  the  whole  of  North  America,  as  far  south  as  the  3Qth 
parallel.  They  generally  occur  as  sands,  clays,  and  gravels, 
spread  in  widely-extended  sheets  over  all  the  geological  forma- 
tions alike,  except  the  most  recent,  and  are  commonly  spoken 
o'f  under  the  general  term  of  "  Glacial  drift."  They  vary  much 


350  HISTORICAL  PALAEONTOLOGY. 

in  their  exact  nature  in  different  districts,  but  they  universally 
consist  of  one,  or  all,  of  the  following  members : — 

1.  Unstratified  clays,,  or  loams,  containing  numerous  angular 
or   sub-angular   blocks   of    stone,   which   have   often   been   trans- 
ported  for   a   greater   or   less   distance    from   their   parent   rock, 
and  which  often  exhibit  polished,  grooved,  or  striated  surfaces. 
These  beds  are  what  is  called  Boulder-clay,  or  Till. 

2.  Sands,   gravels,   and   clays,   often   more   or   less    regularly 
stratified,  but  containing  erratic  blocks,  often  of  large  size,  and 
with   their   edges   unworn,   derived    from   considerable    distances 
from  the  place  where  they  are  now  found.     In  these  beds  it  is 
not  at  all  uncommon  to  find  fossil  shells  ;  and  these,  though  of 
existing  species,  are  generally  of  an  Arctic  character,  compris- 
ing a  greater  or  less  number  of  forms  which  are  now  exclusively 
found  in   the   icy  waters   of  the   Arctic   seas.     These   beds   are 
often  spoken  of  as  "  Stratified  Drift." 

3.  Stratified    sands    and    gravels,    in    which    the    pebbles    are 
worn    and    rounded,    and   which   have    been    produced    by    a    re- 
arrangement  of   ordinary  glacial   beds   by  the   sea.     These  beds 
are    commonly    known    as    "  Drift-gravels,"     or    "  Regenerated 
Drift." 

Some  of  the  last-mentioned  of  these  are  doubtless  post- 
glacial; but,  in  the  absence  of  fossils,  it  is  often  impossible  to 
arrive  at  a  positive  opinion  as  to  the  precise  age  of  superficial 
accumulations  of  this  nature.  It  is  also  the  opinion  of  high 
authorities  that  a  considerable  number  of  the  so-called  "  cave- 
deposits,"  with  the  bones  of  extinct  Mammals,  truly  belong  to 
the  Glacial  period,  being  formed  during  warm  intervals  when 
the  severity  of  the  Arctic  cold  had  become  relaxed.  It  is 
further  believed  that  some,  at  any  rate,  of  the  so-called  "high- 
level  "  river-gravels  and  "  brick-earths "  have  likewise  been 
deposited  during  mild  or  warm  intervals  in  the  great  age  of 
ice ;  and  in  two  or  three  instances  this  has  apparently  been 
demonstrated — deposits  of  this  nature,  with  the  bones  of  ex- 
tinct animals  and  the  implements  of  man,  having  been  shown 
to  be  overlaid  by  true  Boulder-clay. 

The  fossils  of  the  undoubted  Glacial  deposits  are  principally 
shells,  which  are  found  in  great  numbers  in  certain  localities, 
sometimes  with  Foraminifera,  the  bivalved  cases  of  Ostracode 
Crustaceans,  &c.  Whilst  some  of  the  shells  of  the  "Drift" 


THE  QUATERNARY  PERIOD.  351 

are  such  as  now  live  in  the  seas  of  temperate  regions,  others, 
as  previously  remarked,  are  such  as  are  now  only  known  to 
live  in  the  seas  of  high  latitudes;  and  these  therefore  afford 
unquestionable  evidence  of  cold  conditions.  Amongst  these 
Arctic  forms  of  shells  which  characterize  the  Glacial  beds 
may  be  mentioned  Pecten  Islandicus  (fig.  254),  Pecten  Grccn- 
landicus.  Scalaria  Grccnlandica,  Leda  truncata,  Astarte  borealis, 
Tcllina  proximo,  Natica  claitsa.  &c. 


Fig.  254.— Left  valve  of  Pecten  Islandicus.    Glacial  and  Recent. 

III.  POST-GLACIAL  DEPOSITS. — As  the  intense  cold  of  the 
Glacial  period  became  gradually  mitigated,  and  temperate 
conditions  of  the  climate  were  once  more  re-established,  various 
deposits  were  formed  in  the  northern  hemisphere,  which  are 
found  to  contain  the  remains  of  extinct  Mammals,  and  which, 
therefore,  are  clearly  of  Post-Pliocene  age.  To  these  deposits 
the  general  name  of  Post-GIacial  formations  is  given ;  but  it  is 
obvious  that,  from  the  nature  of  the  case,  and  with  our  present 
limited  knowledge,  we  cannot  draw  a  rigid  line  of  demarcation 
between  the  deposits  formed  toward  the  close  of  the  Glacial 
period,  or  during  warm  "  Interglacial  "  periods,  and  those  laid 
down  after  the  ice  had  fairly  disappeared.  Indeed  it  is  ex- 
tremely improbable  that  any  such  rigid  line  of  demarcation 


352  HISTORICAL  PALEONTOLOGY. 

should  ever  have  existed ;  and  it  is  far  more  likely  that  the 
Glacial  and  Post-Glacial  periods,  and  their  corresponding  de- 
posits, shade  into  one  another  by  an  imperceptible  gradation. 
Accepting  this  reservation,  we  may  group  together,  under  the 
general  head  of  "  Post-Glacial  Deposits,"  most  of  the  so-called 
"  Valley-gravels,"  "  Brick-earths,"  and  "  Cave-deposits,"  to- 
gether with  some  "  raised  beaches "  and  various  deposits  of 
peat.  Though  not  strictly  within  the  compass  of  this  work, 
a  few  words  may  be  said  here  as  to  the  origin  and  mode 
of  formation  of  the  Brick-earths,  Valley-gravels,  and  Cave- 
deposits,  as  the  subject  will  thus  be  rendered  more  clearly 
intelligible. 

Every  river  produces  at  the  present  day  beds  of  fine  mud 
and  loam,  and  accumulations  of  gravel,  which  it  deposits  at 
various  parts  of  its  course — the  gravel  generally  occupying  the 
lowest  position,  and  the  finer  sands  and  mud  coming  above. 
Numerous  deposits  of  a  similar  nature  are  found  in  most 
countries  in  various  localities,  and  at  various  heights  above 
the  present  channels  of  our  rivers.  Many  of  these  fluviatile 
(Lat.  fluvius,  a  river)  deposits  consist  of  fine  loam,  worked  for 
brick-making,  and  known  as  "  Brick-earths ;"  and  they  have 
yielded  the  remains  of  numerous  extinct  Mammals,  of  which 
the  Mammoth  (Elcphas  primigenius}  is  the  most  abundant. 
In  the  valley  of  the  Rhine  these  fluviatile  loams  (known  as 
"Loess")  attain  a  thickness  of  several  hundred  feet,  and  con- 
tain land  and  fresh-water  shells  of  existing  species.  With 
these  occur  the  remains  of  Mammals,  such  as  the  Mammoth 
and  Woolly  Rhinoceros.  Many  of  these  Brick-earths  are 
undoubtedly  Post-Glacial,  but  others  seem  to  be  clearly  "  inter- 
glacial ;"  and  instances  have  recently  been  brought  forward  in 
which  deposits  of  Brick-earth  containing  bones  and  sliells  of 
fresh-water  Molluscs  have  been  found  to  be  overlaid  by  regu- 
lar unstratified  boulder-clay. 

The  so-called  "  Valley-gravels,"  like  the  Brick-earths,  are 
fluviatile  deposits,  but  are  of  a  coarser  nature,  consisting  of 
sands  and  gravels.  Every  river  gives  origin  to  deposits  of 
this  kind  at  different  points  along  the  course  of  its  valley; 
and  it  is  not  uncommon  to  find  that  there  exist  in  the  valley 
of  a  single  river  two  or  more  sets  of  these  gravel-beds,  formed 
by -the  river  itself,  but  formed  at  times  when  the  river  ran 
at  different  levels,  and  therefore  formed  at  different  periods. 
These  different  accumulations  are  known  as  the  "  high-level " 
and  "  low-level "  gravels ;  and  a  reference  to  the  accompany- 


THE  QUATERNARY  PERIOD.  353 

ing  diagram  will  explain  the  origin  and  nature  of  these  de- 
posits (fig.  255).  When  a  river  begins  to  occupy  a  particular 
line  of  drainage,  and  to  form  its  own  channel,  it  will  deposit 
fluviatile  sands  and  gravels  along  its  sides.  As  it  goes  on 
deepening  the  bed  or  valley  through  which  it  flows,  it  will 
deposit  other  fluviatile  strata  at  a  lower  level  besides  its  new 
bed.  In  this  way  have  arisen  the  terms  "  high-level "  and 
"  low-level "  gravels.  We  find,  for  instances,  a  modern  river 
flowing  through  a  valley  which  it  has  to  a  great  extent  or 
entirely  formed  itself;  by  the  side  of  its  immediate  channel 


Fig.  255.— Recent  and  Post-Pliocene  Alluvial  Deposits.  1,  Peat  of  the  recent  period  ; 
2,  Gravel  of  the  modern  river  ;  2',  Loam  of  the  modern  river  ;  3,  Lower-level  valley- 
gravel  with  bones  of  extinct  Mammals  (Post-Pliocene)  ;  3',  Loam  of  the  same  age  as  3; 
4,  Higher-level  valley-gravel  (Post-Pliocene)  ;  4'.  Loam  of  the  same  age  as  4  ;  5,  Upland 
gravel  of  various  kinds  (often  glacial  drift) ;  6,  Older  rocks.  (After  Sir  Charles  Lyell.) 

we  may  find  gravels,  sand,  and  loam  (fig.  255,  2  2')  deposited 
by  the  river  flowing  in  its  present  bed.  These  are  recent 
fluviatile  or  alluvial  deposits.  At  some  distance  from  the 
present  bed  of  the  river,  and  at  a  higher  level,  we  may  find 
other  sands  and  gravels,  quite  like  the  recent  ones  in  charac- 
ter and  origin,  but  formed  at  a  time  when  the  stream  flowed 
at  a  higher  level,  and  before  it  had  excavated  its  valley  to  its 
present  depth.  These  (fig.  255,  3  3')  are  the  so-called  "  low- 
level  gravels "  of  a  river.  At  a  still  higher  level,  and  still 
farther  removed  from  the  present  bed  of  the  river,  we  may 
find  another  terrace,  composed  of  just  the  same  materials  as 
the  lower  one,  but  formed  at  a  still  earlier  period,  when  the 
excavation  of  the  valley  had  proceeded  to  a  much  less  extent. 
These  (fig.  255,  4  4')  are  the  so-called  "high-level  gravels" 
of  a  river,  and  there  may  be  one  or  more  terraces  of  these. 

The  important  fact  to  remember  about  these  fluviatile  de- 
posits is  this — that  here  the  ordinary  geological  rule  is  reversed. 
The   high-level   gravels    are,   of   course,    the   highest,    so    far   as 
their    actual    elevation    above    the    sea    is    concerned;    but    geo- 
23 


354  HISTORICAL  PALAEONTOLOGY. 

logically  the  lowest,  since  they  are  obviously  much  older  than 
the  low-level  gravels,  as  these  are  than  the  recent  gravels. 
How  much  older  the  high-level  gravels  may  be  than  the  low- 
level  ones,  it  is  impossible  to  say.  They  occur  at  heights 
varying  from  10  to  100  feet  above  the  present  river-chan- 
nels, and  they  are  therefore  older  than  the  recent  gravels 
by  the  time  required  by  the  river  to  dig  out  its  own  bed  to 
this  depth.  How  long  this  period  may  be,  our  data  do  not 
enable  us  to  determine  accurately ;  but  if  we  are  to  calculate 
from  the  observed  rate  of  erosion  of  the  actually  existing 
rivers,  the  period  between  the  different  valley-gravels  must 
be  a  very  long  one. 

The  lowest  or  recent  fluviatile  deposits  which  occur  beside 
the  bed  of  the  present  river,  are  referable  to  the  Recent  period, 
as  they  contain  the  remains  of  none  but  living  Mammals.  The 
two  other  sets  of  gravels  are  Post-Pliocene,  as  they  contain 
the  bones  of  extinct  Mammals,  mixed  with  land  and  fresh- 
water shells  of  existing  species.  Among  the  more  important 
extinct  Mammals  of  the  low-level  and  high-level  valley-gravels 
may  be  mentioned  the  Elephas  aiitiquus,  the  Mammoth  (Ele- 
phas  primigenius},  the  Woolly  Rhinoceros  (R.  ticJwrhinus),  the 
Hippopotamus,  the  Cave-lion,  and  the  Cave-bear.  Along 
with  these  are  found  unquestionable  traces  of  the  existence 
of  Man,  in  the  form  of  rude  flint  implements  of  undoubted 
human  workmanship. 

The  so-called  "  Cave-deposits,"  again,  though  exhibiting 
peculiarities  due  to  the  fact  of  their  occurrence  in  caverns  or 
fissures  in  the  rocks,  are  in  many  respects  essentially  similar 
to  the  olde,r  valley-gravels.  Caves,  in  the  great  majority  of 
instances,  occur  in  limestone.  When  this  is  not  the  case,  it 
will  generally  be  found  that  they  occur  along  lines  of  sea-coast, 
or  along  lines  which  can  be  shown  to  have  anciently  formed 
the  coast-line.  There  are  many  caves,  however,  in  the  making 
of  which  it  can  be  shown  that  the  sea  has  had  no  hand;  and 
these  are  most  of  the  caves  of  limestone  districts.  These  owe 
their  origin  to  the  solvent  action  upon  lime  of  water  holding 
carbonic  acid  in  solution.  The  rain  which  falls  upon  a  lime- 
stone district  absorbs  a  certain  amount  of  carbonic  acid  from 
the  air,  or  from  the  soil.  It  then  percolates  through  the  rock, 
generally  along  the  lines  of  jointing  so  characteristic  of  lime- 
stones, and  in  its  progress  it  dissolves  and  carries  off  a  certain 
quantity  of  carbonate  of  lime.  In  this  way,  the  natural  joints 
and  fissures  in  the  rock  are  widened,  as  can  be  seen  at  the 


THE  QUATERNARY  PERIOD.  355 

present  day  in  any  or  all  limestone  districts.  By  a  continu- 
ance of  this  action  for  a  sufficient  length  of  time,  caves  may 
ultimately  be  produced.  Nothing,  also,  is  commoner  in  a 
limestone  district  than  for  the  natural  drainage  to  take  the 
line  of  some  fissure,  dissolving  the  rock  in  its  course.  In  this 
way  we  constantly  meet  in  limestone  districts  with  springs 
issuing  from  the  limestone  rock — sometimes  as  large  rivers — 
the  waters  of  which  are  charged  with  carbonate  of  lime,  ob- 
tained by  the  solution  of  the  sides  of  the  fissure  through  which 
the  waters  have  flowed.  By  these  and  similar  actions,  every 
district  in  which  limestones  are  extensively  developed  will  be 
found  to  exhibit  a  number  of  natural  caves,  rents,  or  fissures. 
The  first  element,  therefore,  in  the  production  of  cave-deposits, 
is  the  existence  of  a  period  in  which  limestone  rocks  were 
largely  dissolved,  and  caves  were  formed  in  consequence  of 
the  then  existing  drainage  taking  the  lime  of  some  fissure. 

Secondly,  there  must  have  been  a  period  in  which  various 
deposits  were  accumulated  in  the  caves  thus  formed.  These 
cavern-deposits  are  of  various  nature,  consisting  of  mud, 
loam,  gravel,  or  breccias  of  different  kinds.  In  all  cases,  these 
materials  have  been  introduced  into  the  cave  at  some  period 
subsequent  to,  or  contemporaneous  with,  the  formation  of  the 
cave.  Sometimes  the  cave  communicates  with  the  surface  by 
a  fissure  through  which  sand,  gravel,  &c.,  may  be  washed  by 
rains  or  by  floods  from  some  neighboring  river.  Sometimes 
the  cave  has  been  the  bed  of  an  ancient  stream,  and  the  de- 
posits have  been  formed  as  are  fluviatile  deposits  at  the  surface. 
Or,  again,  the  river  has  formerly  flowed  at  a  greater  elevation 
than  it  does  at  present,  and  the  cave  has  been  filled  with 
fluviatile  deposits  by  the  river  at  a  time  prior  to  the  excava- 
tion of  its  bed  to  the  present  depth  (fig.  256).  In  this  last 
case,  the  cave-deposits  obviously  bear  exactly  the  same  rela- 
tion in  point  of  antiquity  to  recent  deposits,  as  do  the  low- 
level  and  high-level  valley-gravels  to  recent  river-gravels.  In 
any  case,  it  is  necessary  for  the  physical  geography  of  the  dis- 
trict to  change  to  some  extent,  in  order  that  the  cave-deposits 
should  be  preserved.  If  the  materials  have  been  introduced 
by  a  fissure,  the  cave  will  probably  become  ultimately  filled 
to  the  roof,  and  the  aperture  of  admission  thus  blocked  up. 
If  a  river  has  flowed  through  the  cave,  the  surface  configura- 
tion of  the  district  must  be  altered  so  far  as  to  divert  the  river 
into  a  new  channel.  And  if  the  cave  is  placed  in  the  side  of 


356 


HISTORICAL  PALEONTOLOGY. 


a  river-valley,  as  in  fig.  256,  the  river  must  have  excavated 
its  channel  to  such  a  depth  that  it  can  no  longer  wash  out  the 
contents  of  a  cave  even  in  high  floods. 

If  the  cave  be  entirely  filled,  the  included  deposits  generally 
get  more  or  less  completely  cemented  together  by  the  percola- 
tion through  them  of  water  holding  carbonate  of  lime  in  solu- 
tion. If  the  cave  is  only  partially  filled,  the  dropping  of  water 
from  the  roof  holding  lime  in  solution,  and  its  subsequent 


Fig.  256.— Diagrammatic  section  across  a  river-valley  and  cave,  a  a.  Recent  valley- 
graves  near  the  channel  (b)  of  the  existing  river  ;  c,  Cavern,  party  filled  with  cave- 
earth  ;  d  d,  High-level  gravels,  filling  fissures  in  the  limestone,  which  perhaps  com- 
municate in  some  instances  with  the  cave,  and  form  a  channel  by  which  materials  of 
various  kinds  were  introduced  into  it  ;  e  e,  Inclined  beds  of  limestone. 

evaporation,  would  lead  to  the  formation  over  the  deposits 
below  of  a  layer  of  stalagmite,  perhaps  several  inches,  or  even 
feet,  in  thickness.  In  this  way  cave-deposits,  with  their  con- 
tained remains,  may  be  hermetically  sealed  up  and  preserved 
without  injury  for  an  altogether  indefinite  period  of  time 

In  all  caves  in  limestone  in  which  deposits  containing  bones 
are  found,  we  have  then  evidence  of  three  principal  sets  of 
changes.  (i.)  A  period  during  which  the  cave  was  slowly 
hollowed  out  by  the  percolation  of  acidulated  water;  (2.)  A 
period  in  which  the  cave  became  the  channel  of  an  engulfed 
river,  or  otherwise  came  to  form  part  of  the  general  drainage- 
system  of  the  district;  (3.)  A  period  in  which  the  cave  was 
inhabited  by  various  animals. 

As  a  typical  example  of  a  cave  with  fossiliferous  Post- 
Pliocene  deposits,  we  may  take  Kent's  Cavern,  near  Torquay, 
in  which  a  systematic  and  careful  examination  has  revealed  the 
following  sequence  of  accumulations  in  descending  order : — 

(a)  Large  blocks  of  limestone,  which  lie  on  the  floor  of  the 
cave,  having  fallen  from  the  roof,  and  which  are  sometimes 
cemented  together  by  stalagmite, 


FAUNA  OF  THE  POST-PLIOCENE.  357 

(£)  A  layer  of  black  mould,  from  three  to  twelve  inches 
thick,  with  human  bones,  fragments  of  pottery,  stone  and 
bronze  implements,  and  the  bones  of  animals  now  living  in 
Britain.  This,  therefore,  is  a  recent  deposit. 

(c)  A   layer   of    stalagmite,    from   sixteen   to   twenty   inches 
thick,  but  sometimes  as  much  as  five  feet,  containing  the  bones 
of  Man,  together  with  those  of  extinct  Post-Pliocene  Mammals. 

(d)  A  bed  of  red  cave-earth,  sometimes  four  feet  in  thick- 
ness,   with    numerous    bones    of    extinct    Mammals    (Mammoth, 
Cave-bear,  &c.),  together  with  human  implements  of  flint  and 
horn. 

O)  A  second  bed  of  stalagmite,  in  places  twelve  feet  in 
thickness,  with  bones  of  the  Cave-bear. 

(/)  A  red-loam  and  cave-breccia,  with  remains  of  the  Cave- 
bear  and  human  implements. 
t 

The  most  important  Mammals  which  are  found  in  cave- 
deposits  in  Europe  generally,  are  the  Cave-bear,  the  Cave-lion, 
the  Cave-hyaena,  the  Reindeer,  the  Musk-ox,  the  Glutton,  and 
the  Lemming — of  which  the  first  three  are  probably  identical 
with  existing  forms,  and  the  remainder  are  certainly  so — to- 
gether with  the  Mammoth  and  the  Woolly  Rhinoceros,  which 
are  undoubtedly  extinct.  Along  with  these  are  found  the 
implements,  and  in  some  cases  the  bones,  of  Man  himself,  in 
such  a  manner  as  to  render  it  absolutely  certain  that  an  early 
race  of  men  was  truly  contemporaneous  in  Western  Europe 
with  the  animals  above  mentioned. 

IV.  UNCLASSIFIED  POST-PLIOCENE  DEPOSITS. — Apart  from 
any  of  the  afore-mentioned  deposits,  there  occur  other  accumu- 
lations— sometimes  superficial,  sometimes  in  caves — which  are 
found  in  regions  where  a  "  Glacial  period "  has  not  been  fully 
demonstrated,  or  where  such  did  not  take  place;  and  which, 
therefore,  are  not  amenable  to  the  above  classification.  The 
most  important  of  these  are  known  to  occur  in  South  America 
and  Australia  ;  and  though  their  numerous  extinct  Mammalia 
place  their  reference  to  the  Post-Pliocene  period  beyond 
doubt,  their  relations  to  the  glacial  period  and  its  deposits  in 
the  northern  hemisphere  have  not  been  precisely  determined. 


358  HISTORICAL  PALEONTOLOGY. 


CHAPTER  XXII. 
THE  POST-PLIOCENE  PERIOD.— Continued. 

As  regards  the  life  of  the  Post-Pliocene  period,  we  have,  in 
the  first  place,  to  notice  the  effect  produced  throughout  the 
northern  hemisphere  by  the  gradual  supervention  of  the  Glacial 
period.  Previous  to  this  the  climate  must  have  been  temper- 
ate or  warm-temperate;  but  as  the  cold  gradually  came  on, 
two  results  were  produced  as  regards  living  beings  of  the 
area  thus  affected.  In  the  first  place,  all  those  Mammals 
which,  like  the  Mammoth,  the  Woolly  Rhinoceros,  the  Lion, 
the  Hysena,  and  the  Hippopotamus,  require,  at  any  rate,  moder- 
ately warm  conditions,  would  be  forced  to  migrate  southwards 
to  regions  not  affected  by  the  new  state  of  things.  In  the 
second  place,  Mammals  previously  inhabiting  higher  latitudes, 
such  as  the  Reindeer,  the  Musk-ox,  and  the  Lemming,  would 
be  enabled  by  the  increasing  cold  to  migrate  southwards,  and 
to  invade  provinces  previously  occupied  by  the  Elephant  and 
the  Rhinoceros.  A  precisely  similar,  but  more  slowly-executed 
process,  must  have  taken  place  in  the  sea,  the  northern  Mol- 
lusca  moving  southwards  as  the  arctic  conditions  of  the  Glacial 
period  became  established,  whilst  the  forms  proper  to  temperate 
seas  receded.  As  regards  the  readily  locomotive  Mammals, 
also,  it  is  probable  that  this  process  was  carried  on  repeatedly 
in  a  partial  manner,  the  southern  and  northern  forms  alternately 
fluctuating  backwards  and  forwards  over  the  same  area,  in  ac- 
cordance with  the  fluctuations  of  temperature  which  have  been 
shown  by  Mr.  James  Geikie  to  have  characterized  the  Glacial 
period  as  a  whole.  We  can  thus  readily  account  for  the  inter- 
mixture which  is  sometimes  found  of  northern  and  southern  types 
of  Mammalia  in  the  same  deposits,  or  in  deposits  apparently 
synchronous,  and  within  a  single  district.  Lastly,  at  the  final 
close  of  the  arctic  cold  of  the  Glacial  period,  and  the  re-estab- 
lishment of  temperate  conditions  over  the  northern  hemisphere, 
a  reversal  of  the  original  process  took  place — the  northern 
Mammals  retiring  within  their  ancient  limits,  and  the  southern 
forms  pressing  northwards  and  reoccupying  their  original 
domains. 


FAUNA  OF  THE  POST-PLIOCENE.  359 

The  Invertebrate  animals  of  the  Post-Pliocene  deposits  re- 
quire no  further  mention — all  the  known  forms,  except  a  few 
of  the  shells  in  the  lowest  beds  of  the  formation,  being  iden- 
tical with  species  now  in  existence  upon  the  globe.  The  only 
point  of  importance  in  this  connection  has  been  previously 
noticed — namely,  that  in  the  true  Glacial  deposits  themselves 
a  considerable  number  of  the  shells  belong  to  northern  or 
Arctic  types. 

As  regards  the  Vertebrate  animals  of  the  period,  no  extinct 
forms  of  Fishes,  Amphibians,  or  Reptiles  are  known  to  occur, 
but  we  meet  with  both  extinct  Birds  and  extinct  Mammals. 
The  remains  of  the  former  are  of  great  interest,  as  indicating 
the  existence  during  Post-Pliocene  times,  at  widely  remote 
points  of  the  southern  hemisphere,  of  various  wingless,  and  for 
the  most  part  gigantic,  Birds.  All  the  great  wingless  Birds  of 
the  order  Cursores  which  are  known  as  existing  at  the  pres- 
ent day  upon  the  globe,  are  restricted  to  regions  which  are 
either  wholly  or  in  great  part  south  of  the  equator.  Thus  the 
true  Ostriches  are  African ;  the  Rheas  are  South  American ; 
the  Emeus  are  Australian ;  the  Cassowaries  are  confined  to 
Northern  Australia,  Papua,  and  the  Indian  Archipelago ;  the 
species  of  Apteryx  are  natives  of  New  Zealand ;  and  the 
Dodo  and  Solitaire  (wingless,  though  probably  not  true  Cur- 
sores'),  both  of  which  have  been  exterminated  within  histor- 
ical times,  were  inhabitants  of  the  islands  of  Mauritius  and 
Rodriguez,  in  the  Indian  Ocean.  In  view  of  these  facts,  it 
is  noteworthy  that,  so  far  as  known,  all  the  Cursorial  Birds 
of  the  Post-Pliocene  period  should  have  been  confined  to  the 
same  hemisphere  as  that  inhabited  by  the  living  representatives 
of  the  order.  It  is  still  further  interesting  to  notice  that  the 
extinct  forms  in  question  are  only  found  in  geographical  prov- 
inces which  are  now,  or  have  been  within  historical  times,  inhab- 
ited by  similar  types.  The  greater  number  of  the  remains  of 
these  have  been  discovered  in  New  Zealand,  where  there  now 
live  several  species  of  the  curious  wingless  genus  Apteryx;  and 
they  have  been  referred  by  Professor  Owen  to  several  generic 
groups,  of  which  Dinoniis  is  the  most  important  (fig  257). 
Fourteen  species  of  Dinoniis  have  been  described  by  the  dis- 
tinguished palaeontologist  just  mentioned,  all  of  them  being 
large  wingless  birds  of  the  type  of  the  existing  Ostrich,  having 
enormous  powerful  hind-limbs  adapted  for  running,  but  with 
the  wings  wholly  rudimentary,  and  the  breast-bone  devoid  of 
the  keel  or  ridge  which  characterizes  this  bone  in  all  birds 


360  HISTORICAL  PALEONTOLOGY. 

which  fly.  The  largest  species  is  the  Dinornis  giganteus,  one 
of  the  most  gigantic  of  living  or  fossil  birds,  the  shank  (tibia) 
measuring  a  yard  in  length,  and  the  total  height  being  at  least 
ten  feet.  Another  species,  the  Dinornis  elcphantopus  (fig.  257), 
though  not  standing  more  than  about  six  feet  in  height,  was 
of  an  even  more  ponderous  construction — "  the  framework 


Fig.  257. — Skeleton  of  Dinornis  elephantopus,  greatly  reduced.    Post-Pliocene, 
New  Zealand.     (After  Owen.) 

of  the  skeleton  being  the  most  massive  of  any  in  the  whole 
class  of  Birds,"  whilst  "  the  toe-bones  almost  rival  those  of  the 
Elephant"  (Owen).  The  feet  in  Dinornis  were  furnished  with 
three  toes,  and  are  of  interest  as  presenting  us  with  an  un- 
doubted Bird  big  enough  to  produce  the  largest  of  the  foot- 
prints of  the  Triassic  Sandstones  of  Connecticut.  New  Zea- 


FAUNA  OF  THE  POST-PLIOCENE.  361 

land  has  now  been  so  far  explored,  that  it  seems  questionable 
if  it  can  retain  in  its  recesses  any  living  example  of  Dinornis; 
but  it  is  certain  that  species  of  this  genus  were  alive  during  the 
human  period,  and  survived  up  to  quite  a  recent  date.  Not 
only  are  the  bones  very  numerous  in  certain  localities,  but 
they  are  found  in  the  most  recent  and  superficial  deposits,  and 
they  still  contain  a  considerable  proportion  of  animal  matter; 
whilst  in  some  instances  bones  have  been  found  with  the 
feathers  attached,  or  with  the  horny  skin  of  the  legs  still  ad- 
hering to  them.  Charred  bones  have  been  found  in  connec- 
tion with  native  "ovens;"  and  the  traditions  of  the  Maories 
contain  circumstantial  accounts  of  gigantic  wingless  Birds,  the 
"  Moas,"  which  were  hunted  both  for  their  flesh  and  their 
plumage.  Upon  the  whole,  therefore,  there  can  be  no  doubt 
but  that  the  Moas  of  New  Zealand  have  been  exterminated  at 
quite  a  recent  period — perhaps  within  the  last  century —  by  the 
unrelenting  pursuit  of  Man, — a  pursuit  which  their  wingless 
condition  rendered  them  unable  to  evade. 

In  Madagascar,  bones  have  been  discovered  of  another  huge 
wingless  Bird,  which  must  have  been  as  large  as,  or  larger 
than,  the  Dinornis  giganieus,  and  which  has  been  described 
under  the  name  of  JEpiornis  ina.viinns.  With  the  bones  have 
been  found  eggs  measuring  from  thirteen  to  fourteen  inches  in 
diameter,  and  computed  to  have  the  capacity  of  three  Ostrich 
eggs.  At  least  two  other  small  species  of  ^Epiornis  have  been 
described  by  Grandidier  and  Milne-Edwards  as  occurring  in 
Madagascar;  and  they  consider  the  genus  to  be  so  closely  allied 
to  the  Dinornis  of  New  Zealand,  as  to  prove  that  these  regions, 
now  so  remote,  were  at  one  time  united  by  land.  Unlike  New 
Zealand,  where  there  is  the  Apteryx,  Madagascar  is  not  known 
to  possess  any  living  wingless  Birds;  but  in  the  neighboring 
island  of  Mauritius  the  wingless  Dodo  (Didus  ineptus)  has  been 
exterminated  less  than  three  hundred  years  ago;  and  the  little 
island  of  Rodriguez,  in  the  same  geographical  province,  has  in 
a  similar  period  lost  the  equally  wingless  Solitaire  (Pezophaps}, 
both  of  these,  however,  being  generally  referred  to  the  Rasores. 

The  Mammals  of  the  Post-Pliocene  period  are  so  numerous, 
that  in  spite  of  the  many  points  of  interest  which  they  present, 
only  a  few  of  the  more  important  forms  can  be  noticed  here, 
and  that  but  briefly.  The  first  order  that  claims  our  attention 
is  that  of  the  Marsupials,  the  headquarters  of  which  at  the 
present  day  is  the  Australian  province.  In  Oolitic  times 
Europe  possessed  its  small  Marsupials,  and  similar  forms 


362 


HISTORICAL  PALEONTOLOGY. 


existed  in  the  same  area  in  the  Eocene  and  Miocene  periods  ; 
but  if  size  be  any  criterion,  the  culminating  point  in  the  history 
of  the  order  was  attained  during  the  Post-Pliocene  period  in 
Australia.  From  deposits  of 
this  age  there  has  been  disen- 
tombed a  whole  series  of  re- 
mains of  extinct,  and  for  the 
most  part  gigantic,  examples 
of  this  group  of  Quadrupeds. 
Not  to  speak  of  Wombats  and 
Phalangers,  two  forms  stand 
out  prominently  as  represen- 
tatives of  the  Post-Pliocene 
animals  of  Australia.  One  of 
these  is  Diprotodon  (fig.  258),  representing,  with  many  differ- 
ences, the  well-known  modern  group  of  the  Kangaroos.  In 
its  teeth,  Diprotodon  shows  itself  to  be  closely  allied  to  the 


"Fig.  258.— Skull  of  Diprotrxton.  Australia, 
greatly  reduced.  Post- Pliocene.  Australia. 


Fig.  259. — Skull  of  Thylacoleo.    Post-Pliocene.  Australia.     Greatly  reduced. 
(After  Flower.) 

t 

living,  grass-eating  Kangaroos ;  -  but  the  hind-limbs  were  not 
so  disproportionately  long.  In  size,  also,  Diprotodon  must 
have  many  times  exceeded  the  dimensions  of  the  largest  of 
its  living  successors,  since  the  skull  measures  no  less  than 
three  feet  in  length.  The  other  form  in  question  is  Thylacoleo 
(fig.  259),  which  is  believed  by  Professor  Owen  to  belong  to 
the  same  group  as  the  existing  "  Native  Devil  "  (Dasyurns)  of 


FAUNA  OF  THE  POST-PLIOCENE.  363 

Van  Diemen's  Land,  and  therefore  to  have  been  flesh-eating 
and  rapacious  in  its  habits,  through  this  view  is  not  accepted 
by  others.  The  principal  feature  in  the  skull  of  Thylacolco  is 
the  presence,  on  each  side  of  each  jaw,  of  a  single  huge  tooth, 
which  is  greatly  compressed,  and  has  a  cutting  edge.  This 
tooth  is  regarded  by  Owen  as  corresponding  to  the  great  cut- 
ting tooth  of  the  jaw  of  the  typical  Carnivores,  but  Professor 
Flower  considers  that  Thvlacoleo  is  rather  related  to  the  Kan- 


Fig.  260. — MeyatheriumCuvieri.    Post-Pliocene.  South  America. 

garoo-rats.  The  size  of  the  crown  of  the  tooth  in  question  is 
not  less  than  two  inches  and  a  quarter;  and  whether  carnivor- 
ous or  not,  it  indicates  an  animal  of  a  size  exceeding  that  of 
the  largest  of  existing  Lions. 

The  order  of  the  Edentates,  comprising  the  existing  Sloths, 
Ant-eaters,  and  Armadillos,  and  entirely  restricted  at  the  present 
day  to  South  America,  Southern  Asia,  and  Africa,  is  one  alike 
singular  for  the  limited  geographical  range  of  its  members, 
their  curious  habits  of  life,  and  the  well-marked  peculiarities 
of  their  anatomical  structure.  South  America  is  the  metrop- 
olis of  the  existing  forms ;  and  it  is  an  interesting  fact  that  there 
flourished  within  Post-Pliocene  times  in  this  continent,,  and  to 
some  extent  in  North  America  also,  a  marvelous  group  of  ex- 
tinct Edentates,  representing  the  living  Sloths  and  Armadillos, 
but  of  gigantic  size.  The  most  celebrated  of  these  is  the  huge 
Megatherium  Cuvieri  (fig.  260)  of  the  South  American  Pampas. 
The  Megathere  was  a  colossal  Sloth-like  animal  which  attained 
a  length  of  from  twelve  to  eighteen  feet,  with  bones  more  mas- 
sive than  those  of  the  Elephant.  Thus  the  thigh-bone  is 


364  HISTORICAL  PALEONTOLOGY. 

nearly  thrice  the  thickness  of  the  same  bone  in  the  largest 
of  existing  Elephants,  its  circumference  at  its  narrowest  point 
nearly  equalling  its  total  length ;  the  massive  bones  of  the 
shank  (tibia  and  fibula)  are  amalgamated  at  their  extremities; 
the  heel-bone  (calcaneum)  is  nearly  half  a  yard  in  length;  the 
haunch-bones  (ilia)  are  from  four  to  five  feet  across  at  their 
crests;  and  the  bodies  of  the  vertebras  at  the  root  of  the  tail 
are  from  five  to  seven  inches  in  diameter,  from  which  it  has 
been  computed  that  the  circumference  of  the  tail  at  this  part 
might  have  been  from  five  to  six  feet.  The  length  of  the  fore- 
foot is  about  a  yard,  and  the  toes  are  armed  with  powerful 
curved  claws.  It  is  known  now  that  the  Megathere,  in  spite 
of  its  enormous  weight  and  ponderous  construction,  walked, 
like  the  existing  Ant-eaters  and  Sloths,  upon  the  outside  edge 
of  the  fore-feet,  with  the  claws  more  or  less  bent  inwards 
towards  the  palm  of  the  hand.  As  in  the  great  majority  of 
the  Edentate  order,  incisor  and  canine  teeth  are  entirely 
wanting,  the  front  of  the  jaws  being  toothless.  The  jaws, 
however,  are  furnished  with  five  upper  and  four  lower  molar 
teeth  on  each  side.  These  grinding  teeth  are  from  seven  to 
eight  inches  in  length,  in  the  form  of  four-sided  prisms,  the 
crowns  of  which  are  provided  with  well-marked  transverse 
ridges;  and  they  continue  to  grow  during  the  whole  life  of 
the  animal.  There  are  indications  that  the  snout  was  pro- 
longed, and  more  or  less  flexible;  and  the  tongue  was  prob- 
ably prehensile.  From  the  characters  of  the  molar  teeth  it 
is  certain  that  the  Megathere  was  purely  herbivorous  in  its 
habits ;  and  from  the  enormous  size  and  weight  of  the  body, 
it  is  equally  certain  that  it  could  not  have  imitated  its  modern 
allies,  the  Sloths,  in  the  feat  of  climbing,  back  downwards, 
amongst  the  trees.  It  is  clear,  therefore,  that  the  Megathere 
sought  its  sustenance  upon  the  ground ;  and  it  was  originally 
supposed  to  have  lived  upon  roots.  By  a  masterly  piece  of 
deductive  reasoning,  however,  Professor  Owen  showed  that 
this  great  "  Ground-Sloth "  must  have  truly  lived  upon  the 
foliage  of  trees,  like  the  existing  Sloths — but  with  this  differ- 
ence, that  instead  of  climbing  amongst  the  branches,  it  actually 
uprooted  the  tree  bodily.  In  this  tour  de  force,  the  animal 
sat  upon  its  huge  haunches  and  mighty  tail,  as  on  a  tripod, 
and  then  grasping  the  trunk  with  its  powerful  arms,  either 
wrenched  it  up  by  the  roots  or  broke  it  short  off  above  the 
ground.  Marvellous  as  this  may  seem,  it  can  be  shown  that 
every  detail  in  the  skeleton  of  the  Megathere  accords  with  the 


FAUNA  OF  THE  POST-PLIOCENE. 


365 


supposition  that  it  obtained  its  food  in  this  way.  Similar 
habits  were  followed  by  the  allied  Mylodon  (fig.  261),  another 
of  the  great  "  Ground-Sloths,"  which  inhabited  South  America 
during  the  Post-Pliocene  period.  In  most  respects,  the  Mylo- 


Ylg.  261.— Skeleton  of  Mylodon  robuatus.    Post-Pliocene,  South  America. 


don  is  very  like  the  Megathere ;  but  the  crowns  of  the  molar 
teeth  are  flat  instead  of  being  ridged.  The  nearly-related 
genus  Megalonyx,  unlike  the  Megathere,  but  like  the  Mylodon, 
extended  its  range  northwards  as  far  as  the  United  States. 


Fig.  262.— Skeleton  of  Gl>/ptodon  clavtpes.    Post-Pliocene,  South  America. 

Just  as  the  Sloths  of  the  present  day  were  formerly  repre- 
sented in  the  same  geographical  area  by  the  gigantic  Megathe- 


366 


HISTORICAL  PALEONTOLOGY. 


roids,  so  the  little  banded  and  cuirassed  Armadillos  of  South 
America  were  formerly  represented  by  gigantic  species,  con- 
stituting the  genus  Glyptodon.  The  Glyptodons  (fig.  262) 
differed  from  the  living  Armadillos  in  having  no  bands  in 
their  armour,  so  that  they  must  have  been  unable  to  roll 
themselves  up.  It  is  rare  at  the  present  day  to  meet  with  any 
Armadillo  over  two  or  three  feet  in  length ;  but  the  length  of 
the  Glyptodon  clavipes,  from  the  tip  of  the  snout  to  the  end  of 
the  tail,  was  more  than  nine  feet. 

There  are  no  canine  or  incisor  teeth  in  the  Glyptodon,  but 
there  are  eight  molars  on  each  side  of  each  jaw,  and  the  crowns 
of  these  are  fluted  and  almost  trilobed.  The  head  is  covered 
by  a  helmet  of  bony  plates,  and  the  trunk  was  defended  by  an 
armour  of  almost  hexagonal  bony  pieces  united  by  sutures,  and 
exhibiting  special  patterns  of  sculpturing  in  each  species.  The 
tail  was  almost  defended  by  a  similar  armour,  and  the  vertebrae 
were  mostly  fused  together  so  as  to  form  a  cylindrical  bony 
rod.  In  addition  to  the  above-mentioned  forms,  a  number 
of  other  Edentate  animals  have  been  discovered  by  the  re- 
searches of  M.  Lund  in  the  Post-Pliocene  deposits  of  the 
Brazilian  bone-caves.  Amongst  these  are  true  Ant-eaters, 
Armadillos,  and  Sloths,  many  of  them  of  gigantic  size,  and  all 
specifically  or  generically  distinct  from  existing  forms. 


Fig.  263.— Skull  of  the  Tichorhhie  Rhinoceros,  the  horns  being  wanting.    One-tenth  of 
the  natural  size.    Post-Pliocene  deposits  of  Europe  and  Asia. 

Passing  over  the  aquatic  orders  of  the  Sirenians  and  Ce- 
taceans, we  come  next  to  the  great  group  of  the  Hoofed  Quad- 
rupeds, the  remains  of  which  are  very  abundant  in  Post- 
Pliocene  deposits  both  in  Europe  and  North  America. 
Amongst  the  Odd-toed  Ungulates  the  most  important  are 


FAUNA  OF  THE  POST-PLIOCENE.  367 

the  Rhinoceroses,  of  which  three  species  are  known  to  have 
existed  in  Europe  during  the  Post-Pliocene  period.  Two 
of  these  are  the  well-known  Pliocerte  forms,  the  Rhinoceros 
Etruscus  and  the  R.  megarhinus,  still  surviving  in  diminished 
numbers;  but  the  most  famous  is  the  Rhinoceros  tichorhinus 
(fig.  263),  or  so-called  "Woolly  Rhinoceros."  This  species 
is  known  not  only  by  innumerable  bones,  but  also  by  a  car- 
cass, at  the  time  of  its  discovery  complete,  which  was  found 
embedded  in  the  frozen  soil  of  Siberia  towards  the  close  of 
last  century,  and  which  was  partly  saved  from  destruction  by 
the  exertions  of  the  naturalist  Pallas.  From  this,  we  know 
that  the  Tichorhine  Rhinoceros,  like  its  associate  the  Mam- 
moth, was  provided  with  a  coating  of  hair,  and  therefore  was 
enabled  to  endure  a  more  severe  climate  than  any  existing 
species.  The  skin  was  not  thrown  into  the  folds  which  char- 
acterize most  of  the  existing  forms;  and  the  technical  name 
of  the  species  refers  to  the  fact  that  the  nostrils  were  com- 
pletely separated  by  a  bony  partition.  The  head  carried  two 
horns,  placed  one  behind  the  other,  the  front  one  being  un- 
usually large.  As  regards  its  geographical  range,  the  Woolly 
Rhinoceros  is  found  in  Europe  in  vast  numbers  north  of  the 
Alps  and  Pyrenees,  and  it  also  abounded  in  Siberia;  so  that 
it  would  appear  to  be  a  distinctly  northern  form,  and  to  have 
been  adapted  for  a  temperate  climate.  It  is  not  known  to 
occur  in  Pliocene  deposits,  but  it  makes  its  first  appearance 
in  the  Pre-Glacial  deposits,  surviving  the  Glacial  period,  and 
being  found  in  abundance  in  Post-Glacial  accumulations.  It 
was  undoubtedly  a  contemporary  of  the  earlier  races  of  men 
in  Western  Europe ;  and  it  may  perhaps  be  regarded  as  being 
the  actual  substantial  kernel  of  some  of  the  "  Dragons "  of 
fable. 

The  only  other  Odd-toed  Ungulate  which  needs  notice  is 
the  so-called  Equus  fossilis  of  the  Post-Pliocene  of  Europe. 
This  made  its  appearance  before  the  Glacial  period,  and  ap- 
pears to  be  in  reality  identical  with  the  existing  Horse  (Equus 
caballus}.  True  Horses  also  occur  in  the  Post-Pliocene  of 
North  America ;  but,  from  some  cause  or  another,  they  must 
have  been  exterminated  before  historic  times. 

Amongst  the  Even-toed  Ungulates,  the  great  Hippopotamus 
major  of  the  Pliocene  still  continued  to  exist  in  Post-Pliocene 
times  in  Western  Europe;  and  the  existing  Wild  Boar  (Sus 
scrofa},  the  parent  of  our  domestic  breeds  of  Pigs,  appeared 
for  the  first  time.  The  Old  World  possessed  extinct  repre- 


368 


HISTORICAL  PALEONTOLOGY. 


sentatives  of  its  existing  Camels,  and  lost  types  of  the  living 
Llamas  inhabited  South  America.  Amongst  the  Deer,  the 
Post-Pliocene  accumulations  have  yielded  the  remains  of 
various  living  species,  such  as  the  Red  Deer  (Cervus  elaphus), 
the  Reindeer  (Cervus  tarandus},  the  Moose  or  Elk  (Alces 
malchis},  and  the  Roebuck  (Cervus  caprcolus},  together  with 
a  number  of  extinct  forms.  Among  the  latter,  the  great 
"Irish  Elk"  (Cervus  megaceros}  is  justly  celebrated  both  for 


Fig.  264.— Skeleton  of  the  "  Irish  Elk  "  (Cervus  megaceros.)    Post-Pliocene,  Britain. 

its  size  and  for  the  number  and  excellent  preservation  of  its 
discovered  remains.  This  extinct  species  (fig.  264)  has  been 
found  principally  in  peat-mosses  and  Post-Pliocene  lake- 


FAUNA  OF  THE  POST-PLIOCENE  369 

deposits,  and  is  remarkable  for  the  enormous  size  of  the 
spreading  antlers,  which  are  widened  out  towards  their  ex- 
tremities, and  attain  an  expanse  of  over  ten  feet  from  tip  to 
tip.  It  is  not  a  genuine  Elk,  but  is  intermediate  between 
the  Reindeer  and  the  Fallow-deer.  Among  the  existing  Deer 


Fig.  265  .--Skull  of  the  Urus  (Bos  primigeniua) .    Post-Pliocene  and  Recent. 
(After  Owen.) 

of  the  Post-Pliocene,  the  most  noticeable  is  the  Reindeer, 
an  essentially  northern  type,  existing  at  the  present  day  in 
Northern  Europe,  and  also  (under  the  name  of- the  "Caribou") 
in  North-  America.  When  the  cold  of  the  Glacial  period  be- 
came established,  this  boreal  species  was  enabled  to  invade 
Central  and  Western  Europe  in  great  herds,  and  its  remains 
are  found  abundantly  in  cave-earths  and  other  Post-Pliocene 
deposits  as  far  south  as  the  Pyrenees. 

In  addition  to  the  above,  the  Post-Pliocene  deposits  of 
Europe  and  North  America  have  yielded  the  remains  of  vari- 
ous Sheep  and  Oxen.  One  of  the  most  interesting  of  the 
latter  is  the  "Urus"  or  Wild  Bull  (Bos  primigenius.,  fig.  265), 
which,  though  much  larger  than  any  of  the  existing  forms,  is 
believed  to  be  specifically  undistinguishable  from  the  domes- 
tic Ox  (Bos  taurus},  and  to  be  possibly  the  ancestor  of  some 
of  the  larger  European  varieties  of  oxen.  In  the  earlier  part 
of  its  existence  the  Urus  ranged  over  Europe  and  Britain  in 
company  with  the  Woolly  Rhinoceros  and  the  Mammoth ;  but 
it  long  survived  these,  and  does  not  appear  to  have  been 
24 


370  HISTORICAL  PALAEONTOLOGY. 

finally  exterminated  till  about  the  twelfth  century.  Another 
remarkable  member  of  the  Post-Pliocene  Cattle,  also  to  be- 
gin with  an  associate  of  the  Mammoth  and  Rhinoceros,  is 
the  European  Bison  or  "Aurochs"  (Bison  prisons}.  This 
"  maned "  ox  formerly  abounded  in  Europe  in  Post-Glacial 
times,  and  was  not  rare  even  in  the  later  periods  of  the 
Roman  empire,  though  much  diminished  in  numbers ,  and 
driven  back  into  the  wilder  and  more  inaccessible  parts  of  the 
country.  At  present  this  fine  species  has  been  so  nearly 
exterminated  that  it  no  longer  exists  in  Europe  save  in 
Lithuania,  where  its  preservation  has  been  secured  by  rigid 
protective  laws.  Lastly,  the  Post-Pliocene  deposits  have 
yielded  the  remains  of  the  singular  living  animals  which  is 
known  as  the  Musk-ox  or  Musk-sheep  (Ovibos  moschatus). 
At  the  present  day,  the  Musk-ox  is  an  inhabitant  of  the 
"  barren  grounds  "  of  Arctic  America,  and  it  is  remarkable  for 
the  great  length  of  its  hair.  It  is,  like  the  Reindeer,  a  dis- 
tinctively northern  animal ;  but  it  enjoyed  during  the  Glacial 
period  a  much  wider  range  than  it  has  at  the  present  day,  the 
conditions  suitable  for  its  existence  being  then  extended  over 
a  considerable  portion  of  the  northern  hemisphere.  Thus 
remains  of  the  Musk-Ox  are  found  in  greater  or  less  abun- 
dance in  Post-Pliocene  deposits  over  a  great  part  of  Europe, 
extending  even  to  the  south  of  France ;  and  closely-related 
forms  are  found  in  similar  deposits  in  the  United  States. 

Coming  to  the  Proboscideans,  we  find  that  the  Mastodons 
seem  to  have  disappeared  in  Europe  at  the  close  of  the 
Pliocene  period,  or  at  the  very  commencement  of  the  Post- 
Pliocene.  In  the  New  World,  on  the  other  hand,  a  species  of 
Mastodon  (M.  Americanus  or  M.  Ohioticus}  is  found  abun- 
dantly in  deposits  of  Post-Pliocene  age,  from  Canada  to 
Texas.  Very  perfect  skeletons  of  this  species  have  been 
exhumed  from  morasses  and  swamps,  and  large  individuals 
attained  a  length  (exclusive  of  the  tusks)  of  seventeen  feet  and 
a  height  of  eleven  feet,  the  tusks  being  twelve  feet  in  length. 
Remains  of  Elephants  are  also  abundant  in  the  Post-pliocene 
deposits  of  both  the  Old  and  the  New  World.  Amongst  these, 
we  find  in  Europe  the  two  familiar  Pliocene  species,  E.  ineri- 
dionalis  and  E.  antiquus,  still  surviving,  but  in  diminished 
numbers.  With  these  are  found  in  vast  abundance  the  re- 
mains of  the  characteristic  Elephant  of  the  Post-Pliocene,  the 
well-known  "Mammoth"  (Elephas  priniigenius'),  which  is  ac- 
companied in  North  America  by  the  nearly-allied,  but  more 


FAUNA  OF  THE  POST-PLIOCENE. 


37i 


southern  species,  me  Elephas  Americanus.     The  Mammoth   (fig. 
266)    is  considerably  larger  than  the  largest  of  the  living  Ele- 


phants, the  skeleton  being  over  sixteen  feet  in  length,  exclusive 
of  the  tusks,  and  over  nine  feet  in  height.  The  tusks  are  bent 
almost  into  a  circle,  and  are  sometimes  twelve  feet  in  length, 


372 


HISTORICAL  PALAEONTOLOGY. 


measured  along  their  curvature.  In  the  frozen  soil  of  Siberia 
several  carcasses  of  the  Mammoth  have  been  discovered  with 
the  flesh  and  skin  still  attached  to  the  bones,  the  most  cele- 
brated of  these  being  a  Mammoth  which  was  discovered  at  the 
beginning  of  this  century  at  the  mouth  of  the  Lena,  on  the  borders 
of  the  Frozen  Sea,  and  the  skeleton  of  which  is  now  preserved 
at  St.  Petersburg  (fig.  266).  From  the  occurrence  of  the  remains 
of  the  Mammoth  in  vast  numbers  in  Siberia,  it  might  have  been 
safely  inferred  that  this  ancient  Elephant  was  able  to  endure  a  far 
more  rigorous  climate  than  its  existing  congeners.  This  infer- 
ence has,  however,  been  rendered  a  certainty  by  the  specimens 
just  referred  to,  which  show  that  the  Mammoth  was  protected 


Fig.  267.— Molar  tooth  of  the  Mammoth  (Elephaa  primigenlus'),  upper  jaw,  right  side, 
one-third  of  the  naturai  size,    a,  Grinding  surface  ;  6,  Side  view.    Post-Pliocene. 

against  the  cold  by  a  thick  coat  of  reddish-brown  wool,  some 
nine  or  ten  inches  long,  interspersed  with  strong,  coarse  black 
hair  more  than  a  foot  in  length.  The  teeth  of  the  Mammoth 
(fig.  267)  are  of  the  type  of  those  of  the  existing  Indian  Ele- 
phant, and  are  found  in  immense  numbers  in  certain  localities. 
The  Mammoth  was  essentially  northern  in  its  distribution, 
never  passing  south  of  a  line  drawn  through  the  Pyrenees,  the 
Alps,  the  northern  shores  of  the  Caspian,  Lake  Baikal,  Kam- 
schatka,  and  the  Stanovi  Mountains  (Dawkins).  It  occurs  in 
the  Pre-Glacial  forest-bed  of  Cromer  in  Norfolk,  survived  the 
Glacial  period,  and  is  found  abundantly  in  Post-Glacial  de- 


FAUNA  OF  THE  POST-PLIOCENE.  3% 

posits  in  France,  Germany,  Britain,  Russia  in  Europe,  Asia, 
and  North  America,  being  often  associated  with  the  Reindeer, 
Lemming,  and  Musk-Ox.  That  it  survived  into  the  earlier 
portion  of  the  human  period  is  unquestionable,  its  remains 
having  been  found  in  a  great  number  of  instances  associated 
with  implements  of  human  manufacture;  whilst  in  one  instance 
a  recognizable  portrait  of  it  has  been  discovered,  carved  on 
bone. 

Amongst  other  Elephants  which  occur  in  Post-Pliocene  de- 
posits may  be  mentioned,  as  of  special  interest,  the  pigmy 
Elephants  of  Malta.  One  of  these — the  Elephas  Melitensis,  or 
so-called  "  Donkey-Elephant " — was  not  more  than  four  and 
a  half  feet  in  height.  The  other — the  Elephas  Falconeri,  of 
Busk — was  still  smaller,  its  average  height  at  the  withers  not" 
exceeding  two  and  a  half  to  three  feet. 

Whilst  herbivorous  animals  abounded  during  the  Post- 
Pliocene,  we  have  ample  evidence  of  the  coexistence  with 
them  of  a  number  of  Carnivorous  forms,  both  in  the  New  and 
the  Old  World.  The  Bears  are  represented  in  Europe  by  at 
least  three  species,  two  of  which — namely,  the  great  Grizzly 
Bear  (Ursus  jerox}  and  the  smaller  Brown  Bear  (Ursus  arctos} 
— are  in  existence  at  the  present  day.  The  third  species  is  the 
celebrated  Cave-bear  (Ursus  spelaus,  fig.  268),  which  is  now 


Fig.  268. — Skull  of  Unua  spelceus.    Post-Pliocene,  Europe.    One-sixth 
of  the  natural  size. 


extinct.  The  Cave-bear  exceeded  in  its  dimensions  the  largest 
of  modern  Bears;  and  its  remains,  as  its  name  implies,  have 
been  found  mainly  in  cavern-deposits.  Enormous  numbers  of 


374  HISTORICAL  PALEONTOLOGY. 

this  large  and  ferocious  species  must  have  lived  in  Europe  in 
Post-Glacial  times ;  and  that  they  survived  into  the  human 
period,  is  clearly  shown  by  the  common  association  of  their 
bones  with  the  implements  of  man.  They  are  occasionally 
accompanied  by  the  remains  of  a  Glutton  (the  Gulo  sp elans'), 
which  does  not  appear  to  be  really  separable  from  the  existing 
Wolverine  or  Glutton  of  northern  regions  (the  Gulo  luscus}. 
In  addition,  we  meet  with  the  bones  of  the  Wolf,  Fox,  Weasel, 
Otter,  Badger,  Wild  Cat,  Panther,  Hyaena,  and  Lion,  &c., 
together  with  the  extinct  Machairodus  or  "  Sabre-toothed 
Tiger."  The  only  two  of  these  that  deserve  further  mention 
are  the  Hyaena  and  the  Lion.  The  Cave-hyaena  (Hyana 
spelaa,  fig.  269)  is  regarded  by  high  authorities  as  nothing 
more  than  a  variety  of  the  living  Spotted  Hyaena  (H.  crocuta} 
of  South  Africa.  This  well-known  species  inhabited  Britain 
and  a  considerable  portion  of  Europe  during  a  large  part  of 
the  Post-Pliocene  period;  and  its  remains  often  occur  in  great 
abundance.  Indeed,  some  caves,  such  as  the  Kirkdale  Cavern 
in  Yorkshire,  were  dens  inhabited  during  long  periods  by  these 
animals,  and  thus  contain  the  remains  of  numerous  individuals 
and  of  successive  generations  of  Hyaenas,  together  with  in- 
numerable gnawed  and  bitten  bones  of  their  prey.  That  the 


Fig.  269.— Skull  of  Hycena  spelcea,  one-fourth  of  the  natural  size. 
Post-Pliocene,  Europe. 

Cave-hyaena  was  a  contemporary  with  Man  in  Western  Europe 
during  Post-Glacial  times  is  shown  beyond  a  doubt  by  the 
common  association  of  its  bones  with  human  implements. 

Lastly,  the  so-called  Cave-lion  (Felis  Spelcea},  long  supposed 
to   be   a   distinct   species,   has   been    shown   to   be   nothing   more 


FAUNA  OF  THE  POST-PLIOCENE.  375 

than  a  large  variety  of  the  existing  Lion  (Pel  is  leo}.  This 
animal  inhabited  Britain  and  Western  Europe  in  times  pos- 
terior to  the  Glacial  period,  and  was  a  contemporary  of  the 
Cave-hyaena,  Cave-bear,  Woolly  Rhinoceros,  and  Mammoth. 
The  Cave-lion  also  unquestionably  survived  into  the  earlier 
portion  of  the  human  period  in  Europe. 

The  Post-Pliocene  deposits  of  Europe  have  further  yielded 
the  remains  of  numerous  Rodents—  such  as  the  Beaver,  the 
Northern  Lemming,  Marmots,  Mice,  Voles,  Rabbits,  &c.  —  to- 
gether with  the  gigantic  extinct  Beaver  known  as  the  Trogon- 
theriitiu  Cuvieri  (fig.  270).  The  great  Castoroides  Ohioensis  of 

the  Post-Pliocene  of  North 
America  is  also  a  great  ex- 
tinct Beaver,  which  reached 
a  length  of  about  five  feet. 
Lastly,  the  Brazilian  bone- 
caves  have  yielded  the  re- 
mains of  numerous  Rodents 
of  types  now  characteristic 
of  South  America,  such  as 
Guinea-pigs,  Capybaras,  tree- 
inhabiting  Porcupines,  and 
Coypus. 

The  deposits  just  alluded  to  have  further  yielded  the 
remains  of  various  Monkeys,  such  as  Howling  Monkeys, 
Squirrel  Monkeys,  and  Marmosets,  all  of  .which  belong  to  the 
group  of  Quadrumona  which  is  now  exclusively  confined  to 
the  South  American  continent  —  namely,  the  "  Platyrhine  " 
Monkeys. 

\\  e  still  have  very  briefly  to  consider  the  occurrence  of 
Man  in  Post-Pliocene  deposits;  but  before  doing  so,  it  will  be 
well  to  draw  attention  to  the  evidence  afforded  by  the  Post- 
Pliocene  Mammals  as  to  the  climate  of  Western  Europe  at 
this  period.  The  chief  point  which  we  have  to  notice  is,  that 
a  considerable  revolution  of  opinion  has  taken  place  on  this 
point.  It  was  originally  believed  that  the  presence  of  such 
animals  as  Elephants,  Lions,  the  Rhinoceros,  and  the  Hippo- 
potamus afforded  an  irrefragable  proof  that  the  climate  of 
Europe  must  have  been  a  warm  one,  at  any  rate  during  Post- 
Glacial  times.  The  existence,  also,  of  numbers  of  Mammoths 
in  Siberia,  was  further  supposed  to  indicate  that  this  high  tem- 
perature extended  itself  very  far  north.  Upor  the  whole,  how- 
ever, the  evidence  is  against  this  view.  Not  only  is  there  great 


.  270.—  Lower  jaw  of  Trogontherium 


376  HISTORICAL  PALEONTOLOGY. 

difficulty  in  supposing  that  the  Arctic  conditions  of  the  Glacial 
period  were  immediately  followed  by  anything  warmer  than  a 
cold-temperate  climate ;  but  there  is  nothing  in  the  nature  of 
the  Mammals  themselves  which  would  absolutely  forbid  their 
living  in  a  temperate  climate.  The  Hippopotamus  major,  though 
probably  clad  in  hair,  offers  some  difficulty — since,  as  pointed 
out  by  Professor  Busk,  it  must  have  required  a  climate  suffi- 
ciently warm  to  insure  that  the  rivers  were  not  frozen  over  in  the 
winter ;  but  it  was  probably  a  migratory  animal,  and  its  occur- 
rence may  be  accounted  for  by  this.  The  Wooly  Rhinoceros 
and  the  Mammoth  are  known  with  certainty  to  have  been  pro- 
tected with  a  thick  covering  of  wool  and  hair;  and  their  ex- 
tension northwards  need  not  necessarily  have  been  limited  by 
anything  except  the  absence  of  a  sufficiently  luxuriant  vege- 
tation to  afford  them  food.  The  great  American  Mastodon, 
though  not  certainly  known  to  have  possessed  a  hairy  covering, 
has  been  shown  to  have  lived  upon  the  shoots  of  Spruce  and 
Firs,  trees  characteristic  of  temperate  regions — as  shown  by  the 
undigested  food  which  has  been  found  with  its  skeleton,  oc- 
cupying the  place  of  the  stomach.  The  Lions  and  Hyaenas, 
again,  as  shown  by  Professor  Boyd  Dawkins,  do  not  indicate 
necessarily  a  warm  climate.  Wherever  a  sufficiency  of  her- 
bivorous animals  to  supply  them  with  food  can  live,  there  they 
can  live  also ;  and  they  have  therefore  no  special  bearing  upon 
the  question  of  climate.  After  a  review  of  the  whole  evidence, 
Professor  Dawkins  concludes  that  the  nearest  approach  at  the 
present  day  to  the  Post-Pliocene  climate  of  Western  Europe 
is  to  be  found  in  the  climate  of  the  great  Siberian  plains  which 
stretch  from  the  Altai  Mountains  to  the  Frozen  Sea.  "Covered 
by  impenetrable  forests,  for  the  most  part  of  Birch,  Poplar, 
Larch,  and  Pines,  and  low  creeping  dwarf  Cedars,  they  present 
every  gradation  in  climate  from  the  temperate  to  that  in  which 
the  cold  is  too  severe  to  admit  of  the  growth  of  trees,  which 
decrease  in  size  as  the  traveler  advances  northwards,  and  are 
replaced  by  the  grey  mosses  and  lichens  that  cover  the  low 
marshy  'tundras.'  The  maximum  winter  cold,  registered  by 
Admiral  Von  Wrangel  at  Nishne  Kolymsk,  on  the  banks  of 
the  Kolyma,  is — 65°  in  January.  '  Then  breathing  becomes 
difficult;  the  Reindeer,  that  citizen  of  the  Polar  region,  with- 
draws to  the  deepest  thicket  of  the  forest,  and  stands  there 
motionless  as  if  deprived  of  life ;'  and  trees  burst  asunder  with 
the  cold.  Throughout  this  area  roam  Elks,  Black  Bears, 
Foxes,  Sables,  and  Wolves,  that  afford  subsistence  to  the 


FAUNA  OF  THE  POST-PLIOCENE.  377 

Jakutian  and  Tungusian  fur-hunters.  In  the  northern  part 
countless  herds  of  Reindeer,  Elks,  Foxes,  and  Wolverines 
make  up  for  the  poverty  of  vegetation  by  the  rich  abundance 
of  animal  life.  '  Enormous  flights  of  Swans,  Geese,  and  Ducks 
arrive  in  the  spring,  and  seek  deserts  where  they  may  moult 
and  build  their  nests  in  safety.  Ptarmigans  run  in  troops 
amongst  the  bushes ;  little  Snipes  are  busy  along  the  brooks 
and  in  the  morasses;  the  social  Crows  seek  the  neighborhood 
of  new  habitations ;  and  when  the  sun  shines  in  spring,  one 
may  even  sometimes  hear  the  cheerful  note  of  the  Finch,  and 
in  autumn  that  of  the  Thrush.'  Throughout  this  region  of 
woods,  a  hardy,  middle-sized  breed  of  horses  lives  under  the 
mastership  and  care  of  man,  and  is  eminently  adapted  to  bear 
the  severity  of  the  climate.  .  .  .  The  only  limit  to  their 
northern  range  is  the  difficulty  of  obtaining  food.  The  severity 
of  the  winter  through  the  southern  portion  of  this  vast  wooded 
area  is  almost  compensated  for  by  the  summer  heat  and  its 
marvellous  effect  on  vegetation." — (Dawkins,  '  Monograph  of 
Pleistocene  Mammalia.') 

Finally,  a  few  words  must  be  said  as  to  the  occurrence  of  the 
remains  of  Man  in  Post-Pliocene  deposits.  That  Man  existed 
in  Western  Europe  and  in  Britain  during  the  Post-pliocene 
period,  is  placed  beyond  a  doubt  by  the  occurrence  of  his  bones 
in  deposits  of  this  age,  along  with  the  much  more  frequent 
occurrence  of  implements  of  human  manufacture.  At  what 
precise  point  of  time  during  the  Post-Pliocene  period  he  first 
made  his  appearance  is  still  a  matter  of  conjecture.  Recent 
researches  would  render  it  probable  that  the  early  inhabitants 
of  Britain  and  Western. Europe  were  witnesses  of  the  stupend- 
ous phenomena  of  the  Glacial  period ;  but  this  cannot  be  said 
to  have  been  demonstrated.  That  Man  existed  in  these 
regions  during  the  Post-Glacial  division  of  Post-Pliocene  time 
cannot  be  doubted  for  a  moment.  As  to  the  physical  peculi- 
arities of  the  ancient  races  that  lived  with  the  Mammoth  and 
the  Woolly  Rhinoceros,  little  is  known  compared  with  what 
we  may  some  day  hope  to  know.  Such  information  as  we 
have,  however,  based  principally  on  the  skulls  of  the  Engis, 
Neanderthal,  Cro-Magnon,  and  Bruniquel  caverns,  would  lead 
to  the  conclusion  that  Post-Pliocene  Man  was  in  no  respect 
inferior  in  his  organization  to,  or  less  highly  developed  than, 
many  existing  races.  All  the  known  skulls  of  this  period,  with 
the  single  exception  of  the  Neanderthal  cranium,  are  in  all 
respects  average  and  normal  in  their  characters ;  and  even  the 


378  HISTORICAL  PALEONTOLOGY. 

Neanderthal  skull  possessed  a  cubic  capacity  at  least  equal  to 
that  of  some  existing  races.  The  implements  of  Post-Pliocene 
Man  are  exclusively  of  stone  or  bone;  and  the  former  are 
invariably  of  rude  shape  and  undressed.  These  "  palaeolithic " 
tools  (Gr.  palaios,  ancient;  lithos,  stone)  point  to  a  very  early 
condition  of  the  arts ;  since  the  men  of  the  earlier  portion 
of  the  Recent  period,  though  likewise  unacquainted  with  the 
metals,  were  in  the  habit  of  polishing  or  dressing  the  stone 
implements  which  they  fabricated. 

It  is  impossible  here  to  enter  further  into  this  subject;  and 
it  would  be  useless  to  do  so  without  entering  as  well  into  a 
consideration  of  the  human  remains  of  the  Recent  period — a 
period  which  lies  outside  of  the  province  of  the  present  work.  So 
far  as  Post-Pliocene  Man  is  concerned,  the  chief  points  which 
the  palseontological  student  has  to  remember  have  been  else- 
where summarized  by  the  author  as  follows  : — 

1.  Man   unquestionably  existed   during   the   later   portion   of 
what  Sir  Charles  Lyell  has  termed  the  "  Post-Pliocene  "  period. 
In    other   words,    Man's    existence    dates    back   to    a    time    when 
several    remarkable    Mammals,    previously    mentioned,    had    not 
yet    become    extinct ;    but    he    does    not    date    back    to    a    time 
anterior  to  the  present  Mollusc  an  fauna. 

2.  The    antiquity    of    the    so-called    Post-Pliocene    period    is 
a    matter    which    must    be    mainly    settled    by    the    evidence    of 
Geology  proper,  and  need  not  be  discussed  here. 

3.  The    extinct    Mammals    with    which    man    coexisted    in 
Western   Europe   are   mostly   of   large   size,   the   most   important 
being  the  Mammoth   (Elephas  priniigenius},  the  Woolly  Rhino- 
ceros (Rhinoceros  tichorhinus},  the  Cave-lion  (Felis  spelcea},  the 
Cave-hyaena  (Hycena  sj>elaa),B.nd  the  Cave-bear  (Ursusspelcuus). 
We    do    not    know    the    cause    which    led    to    the    extinction    of 
these    Mammals ;    but    we    know    that    hardly    any    Mammalian 
species  has  become  extinct  during  the  historical  period. 

4.  The  extinct  Mammals  with  which  man  coexisted  are  re- 
ferable in  many  cases  to  species  which  presumably  required   a 
very  different  climate  to  that  now  prevailing  in  Western  Europe. 
How  long  a  period,  however,  has  been  consumed  in  the  bring- 
ing about   of  the   climatic   changes   thus   indicated,   we   have   no 
means  of  calculating  with  any  approach  to  accuracy. 

5.  Some  of  the  deposits  in  which  the  remains  of  man  have 
been   found  associated  with  the  bones  of  extinct  Mammals,  are 
such   as   to   show   incontestable  that  great  changes   in   the   phy- 
sical   geography    and    surface-configuration    of    Western    Europe 


FAUNA  OF  THE  POST-PLIOCENE.  379 

have  taken  place  since  the  period  of  their  accumulation.  \Vc 
have,  however,  no  means  at  present  of  judging  of  the  lapse  of 
time  thus  indicated  except  by  analogies  and  comparisons  which 
may  be  disputed. 

6.  The    human    implements    which    are    associated    with    the 
remains  of  extinct   Mammals,  themselves  bear  evidence  of     an 
exceedingly  barbarous   condition   of   the   human   species.      Post- 
Pliocene  or  "  Palaeolithic "   Man  was  clearly  unacquainted  with 
the  use  of  any  of  the  metals.     Not  only  so,  but  the  workman- 
ship of  these  ancient  races  was   much  inferior  to  that  of   the 
later   tribes,    who    were   also   ignorant   of    the   metals,   and   who 
also  used  nothing  but  weapons  and  tools  of  stone,  bone,  &c. 

7.  Lastly,  it  is  only  with  the  human  remains  of  the   Post- 
Fliocene    period    that    the    palaeontologist    proper    has    to    deal. 
V  hen  we  enter  the  "Recent"  period,  in  which  the  remains  of 
Man  are  associated  with  those  of  existing  species  of  Mammals, 
we  pass  out  of  the   region  of  pure  palaeontology  into  the  do- 
main of  the  Archaeologist  and  the  Ethnologist. 

LITERATURE. 

The  following  are  some  of  the  principal  works  and  memoirs 
to  which  the  student  may  refer  for  information  as  to  the  Post- 
Pliocene  deposits  and  the  remains  which  they  contain,  as  well  as 
the  primitive  races  of  mankind : — 

(1)  'Elements  of  Geology.'     Lyell. 

(2)  '  Antiquity  of  Man.'     Lyell. 

(3)  Talaeontological  Memoirs.'     Falconer. 

(4)  '  The  Great  Ice-age.'    James  Geikie. 

(5)  '  Manual  of  Palaeontology.'     Owen. 

(6)  '  British  Fossil  Mammals  and  Birds/     Owen. 

(7)  '  Cave-Hunting.'     Boyd  Dawkins. 

(8)  '  Prehistoric  Times.'    Lubbock. 

(9)  '  Ancient  Stone  Implements.'    Evans. 

(10)  'Prehistoric  Man.'    Daniel  Wilson. 

(n)   'Prehistoric  Races  of  the  United  States.'     Foster. 

(12)  'Manual  of  Geology.'    Dana. 

(13)  'Monograph    of    Pleistocene    Mammalia.'     (Palaeonto- 

graphical  Society).    Boyd  Dawkins  and  Sanford. 

(14)  '  Monograph    of    the    Post-Tertiary    Entomostraca    of 

Qcotland,  &c.,  with  an  Introduction  on  the  Post- 
Tertiary  Deposits  of  Scotland'  (Ibid.)  G.  S.  Brady, 
H.  W.  Crosskey,  and  D.  Robertson. 

(15)  "Reports  on  Kent's  Cavern  "--'  British  Association  Re- 

ports.'    Pengelly. 

(16)  "Reports    on    the    Victoria    Cavern,    Settle" — 'British 

Association  Reports.'    Tiddeman. 

(17)  '  Ossemens  Fossiles.'     Cuvier. 


3&>  HISTORICAL  PALEONTOLOGY. 

(18)  '  Reliquiae  Diluvianae.'    Buckland. 

(19)  "Fossil  Mammalia "— '  Zoology  of  the  Voyage  of  the 

Beagle.'    Owen. 

(20)  'Description  of  the  Tooth  and  Part  of  the  Skeleton  of 

the  Glyptodon'    Owen. 

(21)  "Memoir    on     the    Extinct     Sloth    Tribe     of     North 

America " — '  Smithsonian    Contributions    to    Knowl- 
edge.'   Leidy. 

(22)  "Report  on  Extinct  Mammals  of  Australia  "—'British 

Association, '  1844.     Owen. 

(23)  'Description   of  the   Skeleton  of  an   Extinct  Gigantic 

Sloth   (Mylodon  robustus).'     Owen. 

(24)  "Affinities    and    Probable    Habits    of    Thylacoleo  "— 

'  Quart.  Journ.  Geol.  Soc.,'  vol.  xxiv.    Flower. 

(25)  '  Prodromus  of  the  Palaeontology  of  Victoria.'    M'Coy. 

(26)  'Les     Ossemens     Fossiles     des     Cavernes     de     Liege.' 

Schmerling. 

(27)  'Die   Fauna   der    Pfahlbauten   in   der    Schweiz.'   Riiti- 

meyer. 

(28)  "  Extinct  and  Existing  Bovine  Animals  of  Scandinavia  " 

— '  Annals  of  Natural  History,'  ser.  2,  vol.  iv.,  1849. 
Nilsson. 

(29)  '  Man's  Place  in  Nature.'     Huxley. 

(30)  'Les  Temps  Antehistoriques  en  Belgique.'    Dupont. 

(31)  "Classification  of  the  Pleistocene  Strata  of  Britain  and 

the     Continent " — '  Quart.    Journ.     Geol.     Soc.,'     vol. 
xxviii.     Boyd  Dawkins. 

(32)  'Distribution  of  the   Post-Glacial   Mammalia'    (Ibid.) 

vol.  xxv.     Boyd  Dawkins. 

(33)  '  On  British  Fossil  Oxen'  (Ibid.),  vols.  xxii.  and  xxiii. 

Boyd  Dawkins. 

(34)  'British    Prehistoric    Mammals'     (Congress    of    Pre- 

historic Archaeology,  1868).    Boyd  Dawkins. 

(35)  'Reliquiae  Aquitanicae.'    Lartet  and  Christy. 

(36)  '  Zoologie  et  Paleontologie  Frangaises.'    Gervais. 

(37)  '  Notes    on    the    Post- Pliocene    Geology    of    Canada.' 

Dawson. 

(38)  "  On  the  Connection  between  the  existing  Fauna  and 

Flora     of     Great     Britain     and     certain     Geological 
Changes  " — '  Mem.  Geol.  Survey.'     Edward  Forbes. 

(39)  '  Cavern-Researches.'     M'Enery.     Edited  by  Vivian. 

(40)  "  Quaternary  Gravels  " — '  Quart.  Journ.  Geol.  Soc./  vol. 

xxv.    Tylor. 


SUCCESSION  OF  LIFE  UPON  THE  GLOBE.        381 


CHAPTER  XXIII. 

THE  SUCCESSION  OF  LIFE  UPON  THE  GLOBE. 

In  conclusion,  it  may  not  be  out  of  place  if  we  attempt  to 
summarize,  in  the  briefest  possible  manner,  some  of  the  prin- 
cipal results  which  may  be  deduced  as  to  the  succession  of 
life  upon  the  earth  from  the  facts  which  have  in  the  preceding 
portion  of  this  work  been  passed  in  review.  That  there  was 
a  time  when  the  earth  was  void  of  life  is  universally  admitted, 
though  it  may  be  that  the  geological  record  gives  us  no  direct 
evidence  of  this.  That  the  globe  of  to-day  is  peopled  with 
innumerable  forms  of  life  whose  term  of  existence  has  been, 
for  the  most  part,  but  as  it  were  of  yesterday,  is  likewise  an 
assertion  beyond  dispute.  Can  we  in  any  way  connect  the 
present  with  the  remote  past,  and  can  we  indicate  even  im- 
perfectly the  conditions  and  laws  under  which  the  existing 
order  was  brought  about?  The  long  series  of  fossiliferous 
deposits,  with  their  almost  countless  organic  remains,  is  the 
link  between  what  has  been  and  what  is;  and  if  any  answer 
to  the  above  question  can  be  arrived  at,  it  will  be  by  the 
careful  and  conscientious  study  of  the  facts  of  Palaeontology. 
In  the  present  state  of  our  knowledge,  it  may  be  safely  said 
that  anything  like  a  dogmatic  or  positive  opinion  as  to  the 
precise  sequence  of  living  forms  upon  the  globe,  and  still 
more  as  to  the  manner  in  which  this  sequence  may  have  been 
brought  about,  is  incapable  of  scientific  proof.  There  are, 
however,  certain  general  deductions  from  the  known  facts 
which  may  be  regarded  as  certainly  established. 

In  the  first  place,  it  is  certain  that  there  has  been  a  succession 
of  life  upon  the  earth,  different  specific  and  generic  types  suc- 
ceeding one  another  in  successive  periods.  It  follows  from 
this,  that  the  animals  and  plants  with  which  we  are  familiar  as 
living,  were  not  always  upon  the  earth,  but  that  they  have  been 
preceded  by  numerous  races  more  or  less  differing  from  them. 
What  is  true  of  the  species  of  animals  and  plants,  is  true  also 
of  the  higher  zoological  divisions;  and  it  is,  in  the  second 


382  HISTORICAL  PALAEONTOLOGY. 

place,  quite  certain  that  there  has  been  a  similar  succession  in 
the  order  of  appearance  of  the  primary  groups  ("  sub-king- 
doms," "classes,"  &c.)  of  animals  and  •  vegetables.  These 
great  groups  did  not  all  come  into  existence  at  once,  but  they 
made  their  appearance  successively.  It  is  true  that  we  can- 
not be  said  to  be  certainly  acquainted  with  the  first  absolute 
appearance  of  any  great  group  of  animals.  No  one  dare 
assert  positively  that  the  apparent  first  appearance  of  Fishes 
in  the  Upper  Silurian  is  really  their  first  introduction  upon  the 
earth :  indeed,  there  is  a  strong  probability  against  any  such 
supposition.  To  whatever  extent,  however,  future  discoveries 
may  push  back  the  first  advent  of  any  or  all  of  the  great 
groups  of  life,  there  is  no  likelihood  that  anything  will  be  found 
out  which  will  materially  alter  the  relative  succession  of  these 
groups  as  at  present  known  to  us.  It  is  not  likely,  for 
example,  that  the  future  has  in  store  for  us  any  discovery  by 
which  it  would  be  shown  that  Fishes  were  in  existence  before 
Molluscs,  or  that  Mammals  made  their  appearance  before 
Fishes.  The  sub-kingdoms  of  Invertebrate  animals  were  all 
represented  in  Cambrian  times — and  it  might  therefore  be  in- 
ferred that  these  had  all  come  simultaneously  into  existence ; 
but  it  is  clear  that  this  inference,  though  incapable  of  actual 
disproof,  is  in  the  last  degree  improbable.  Anterior  to  the 
Cambrian  is  the  great  series  of  the  Laurentian,  .which,  owing 
to  the  metamorphism  to  which  it  has  been  subjected,  has  so 
far  yielded  but  the  singular  Eozo'dn.  We  may  be  certain, 
however,  that  others  of  the  Invertebrate  sub-kingdoms  besides 
the  Protozoa  were  in  existence  in  the  Laurentian  period ;  and 
we  may  infer  from  known  analogies  that  they  appeared  suc- 
cessively, and  not  simultaneously. 

When  we  come  to  smaller  divisions  than  the  sub-king- 
doms— such  as  classes,  orders,  and  families — a  similar  suc- 
cession of  groups  is  observable.  The  different  classes  of 
any  given  sub-kingdom,  or  the  different  orders  of  any  given 
class,  do  not  make  their  appearance  together  and  all  at  once, 
but  they  are  introduced  upon  the  earth  in  succession.  More 
than  this,  the  different  classes  of  a  sub-kingdom,  or  the  differ- 
ent orders  of  a  class,  in  the  main  succeed  one  another  in  the 
relative  order  of  their  zoological  rank — the  lower  groups  appear- 
ing first  and  the  higher  groups  last.  It  is  true  that  in  the 
Cambrian  formation — the  earliest  series  of  sediments  in  which 
fossils  are  abundant — we  find  numerous  groups,  some  very 
low,  others  very  high,  in  the  zoological  scale,  which  appear 


SUCCESSION  OF  LIFE  UPON  THE  GLOBE.        383 

to  have  simultaneously  flashed  into  existence.  For  reasons 
stated  above,  however,  we  cannot  accept  this  appearance  as 
real ;  and  we  must  believe  that  many  of  the  Cambrian  groups 
of  animals  really  came  into  being  long  before  the  commence- 
ment of  the  Cambrian  period.  At  any  rate,  in  the  long  series 
of  fossiliferous  deposits  of  later  date  than  the  Cambrian  the 
above-stated  rule  holds  good  as  a  broad  generalization — that 
the  lower  groups,  namely,  precede  the  higher  in  point  of  time ; 
and  though  there  are  apparent  exceptions  to  the  rule,  there 
are  none  of  such  a  nature  as  not  to  admit  of  explanation. 
Some  of  the  leading  facts  upon  which  this  generalization  is 
founded  will  be  enumerated  immediately;  but  it  will  be  well, 
in  the  first  place,  to  consider  briefly  what  we  precisely  mean 
when  we  speak  of  "  higher  "  and  "  lower  "  groups. 

It  is  well  known  that  naturalists  are  in  the  habit  of  "  clas- 
sifying" the  innumerable  animals  which  now  exist  upon  the 
globe;  or,  in  other  words,  of  systematically  arranging  them  into 
groups.  The  precise  arrangement  adopted  by  one  naturalist 
may  differ  in  minor  details  from  that  adopted  by  another;  but 
all  are  agreed  as  to  the  fundamental  points  of  classification, 
and  all,  therefore,  agree  in  placing  certain  groups  in  a  certain 
sequence.  What,  then,  is  the  principle  upon  which  this 
sequence  is  based  ?  Why,  for  example,  are  the  Sponges  placed 
below  the  Corals;  these  below  the  Sea-Urchins ;  and  these,  again, 
below  the  Shell-fish?  W'ithout  entering  into  a  discussion  of 
the  principles  of  zoological  classification,  which  would  here  be 
out  of  place,  it  must  be  sufficient  to  say  that  the  sequence  in 
question  is  based  upon  the  relative  type  of  organisation  of  the 
groups  of  animals  classified.  The  Corals  are  placed  above  the 
Sponges  upon  the  ground  that,  regarded  as  a  whole,  the  plan 
or  type  of  structure  of  a  Coral  is  more  complex  than  that  of  a 
Sponge.  It  is  not  in  the  slightest  degree  that  the  Sponge  is  in 
any  respect  less  highly  organized  or  less  perfect,  as  a  Sponge, 
than  is  the  Coral  as  a  Coral  ?  Each  is  equally  perfect  in  its 
own  way;  but  the  structural  pattern  of  the  Coral  is  the  highest, 
and  therefore  it  occupies  a  higher  place  in  the  zoological  scale. 
It  is  upon  this  principal,  then,  that  the  primary  subdivisions 
of  the  animal  kingdom  (the  so-called  "sub-kingdoms")  are 
arranged  in  a  certain  order.  Coming,  again,  to  the  minor 
subdivisions  (classes,  orders,  &c.)  of  each  sub-kingdom,  we 
find  a  different  but  entirely  analogous  principal  employed  as  a 
means  of  classification.  The  numerous  animals  belonging  to 
any  given  sub-kingdom  are  formed  upon  the  same  fundamental 


384  HISTORICAL  PALAEONTOLOGY. 

plan  of  structure ;  but  they  nevertheless  admit  of  being  ar- 
ranged in  a  regular  series  of  groups.  All  the  Shell-fish,  for 
example,  are  built  upon  a  common  plan,  this  plan  representing 
the  ideal  Mollusc;  but  there  are  at  the  same  time  various 
groups  of  the  Mollusca,  and  these  groups  admit  of  an  arrange- 
ment in  a  given  sequence.  The  principle  adopted  in  this  case 
is  simply  of  the  relative  elaboration  of  the  common  type.  The 
Oyster  is  built  upon  the  same  ground-plan  as  the  Cuttle-fish ;  but 
this  plan  is  carried  out  with  much  greater  elaboration,  and  with 
many  more  complexities,  in  the  latter  than  in  the  former:  and 
in  accordance  with  this,  the  Cephalopoda  consistitute  a  higher 
group  than  the  Bivalve  Shell-fish.  As  in  the  case  of  superiority 
of  structural  type,  so  in  this  case  also,  it  is  not  in  the  least  that 
the  Oyster  is  an  imperfect  animal.  On  the  contrary,  it  is  just 
as  perfectly  adapted  by  its  organization  to  fill  its  own  sphere 
and  to  meet  the  exigencies  of  its  own,  existence  as  is  the 
Cuttle-fish;  but  the  latter  lives  a  life  which  is,  physiologically, 
higher  than  the  former,  and  its  organization  is  correspondingly 
increased  in  complexity. 

This  being  understood,  it  may  be  repeated  that,  in  the 
main,  the  succession  of  life  upon  the  globe  in  point  of  time 
has  corresponded  with  the  relative  order  of  succession  of  the 
great  groups  of  animals  in  zoological  rank;  and  some  of  the 
more  striking  examples  of  this  may  be  here  alluded  to. 
Amongst  the  Echinoderms,  for  instance,  the  two  orders  gen- 
erally admitted  to  be  the  "  lowest "  in  the  zoological  scale — 
namely,  the  Crinoids  and  the  Cystoids — are  likewise  the  oldest, 
both  appearing  in  the  Cambrian,  the  former  slowly  dying  out 
as  we  approach  the  Recent  period,  and  the  latter  disappearing 
wholly  before  the  close  of  the  Palaeozoic  period.  Amongst  the 
Crustaceans,  the  ancient  groups  of  the  Trilobites,  Ostracodes, 
Phyllopods,  Eurypterids,  and  Limuloids,  some  of  which  exist 
at  the  present  day,  are  all  "  low "  types ;  whereas  the  highly- 
organized  Decapods  do  not  make  their  appearance  till  the  near  the 
close  of  the  Palaeozoic  epoch,  and  they  do  not  become  abun- 
dant till  we  reach  Mesozoic  times.  Amongst  the  Mollusca, 
those  Bivalves  which  possess  breathing-tubes  (the  "  siphonate " 
Bivalves)  are  generally  admitted  to  be  higher  than  those  which 
are  destitute  of  these  organs  (the  "  asiphonate  "  Bivalves)  ;  and 
the  latter  are  especially  characteristic  of  the  Palaeozoic  period, 
whilst  the  former  abound  in  Mesozoic  and  Kainozoic  forma- 
tions. Similarly,  the  Univalves  with  breathing-tubes  and  a 
corresponding  notch  in  the  mouth  of  the  shell  ("  siphonosto- 


SUCCESSION  OF  LIFE  UPON  THE  GLOBE.        385 

matous "  Univalves)  are  regarded  as  higher  in  the  scale  than 
the  round-mouthed  vegetable-eating  Sea-snails,  in  which  no 
respiratory  siphons  exist  ("  holostomatous "  Univalves)  ;  but 
the  latter  abound  in  the  Palaeozoic  rocks — whereas  the  former 
do  not  make  their  appearance  till  the  Jurassic  period,  and 
their  higher  groups  do  not  seem  to  have  existed  till  the  close 
of  the  Cretaceous.  The  Cephalopods,  again — the  highest  of  all 
the  groups  of  Mollusca — are  represented  in  the  Palaeozoic 
rocks  exclusively  by  Tetrabranchiate  forms,  which  constitute 
the  lowest  of  the  two  orders  of  this  class;  whereas  the  more 
highly  specialized  Dibranchiates  do  not  make  their  appearance 
till  the  commencement  of  the  Mesozoic.  The  Palaeozoic 
Tetrabranchiates,  also  are  of  a  much  simpler  type  than  the 
highly  complex  Ammonitidce  of  the  Mesozoic. 

Similar  facts  are  observable  amongst  the  Vertebrate  animals. 
The  Fishes  are  the  lowest  class  of  Vertebrates,  and  they  are 
the  first  to  appear,  their  first  certain  occurrence  being  in  the 
Upper  Silurian ;  whilst,  even  if  the  Lower  Silurian  and  Upper 
Cambrian  "  Conodonts  "  were  shown  to  be  the  teeth  of  Fishes, 
there  would  still  remain  the  enormously  long  periods  of  the 
Laurentian  and  Lower  Cambrian,  during  which  there  were  In- 
vertebrates, but  no  Vertebrates.  The  Amphibians,  the  next 
class  in  zoological  order,  appears  later  than  the  Fishes,  and 
is  not  represented  till  the  Carboniferous ;  whilst  its  highest 
group  (that  of  the  Frogs  and  Toads)  does  not  make  its  entrance 
upon  the  scene  till  Tertiary  times  are  reached.  The  class  of 
the  Reptiles,  again,  the  next  in  order,  does  not  appear  till 
the  Permian,  and  therefore  not  till  after  Amphibians  of  very 
varied  forms  had  been  in  existence  for  a  protracted  period. 
The  Birds  seem  to  be  undoubtedly  later  than  the  Reptiles; 
but,  owing  to  the  uncertainty  as  to  the  exact  point  of  their  first 
appearance,  it  cannot  be  positively  asserted  that  they  pre- 
ceded Mammals,  as  they  should  have  done.  Finally,  the 
Mesozoic  types  of  Mammals  are  mainly,  if  not  exclusively, 
referable  to  the  Marsupials,  one  of  the  lowest  orders  of  the 
class ;  whilst  the  higher  orders  of  the  "  Placental  "  Quadrupeds 
are  not  with  certainty  known  to  have  existed  prior  to  the  com- 
mencement of  the  Tertiary  period. 

Facts  of  a  very  similar  nature  are  offered  by  the  succession 
of  Plants  upon  the  globe.  Thus  the  vegetation  of  the  Palaeo- 
zoic period  consisted  principally  of  the  lowly-organized  groups 
of  the  Cryptogamous  or  Flowerless  plants.  The  Mesozoic 
formations,  up  to  the  Chalk,  are  especially  characterized  by  the 
25 


386  HISTORICAL  PALEONTOLOGY. 

naked-seeded  Flowering  plants — the  Conifers  and  the  Cycads; 
whilst  the  higher  groups  of  the  Angiospermous  Exogens  and 
Monocotyledons  characterize  the  Upper  Cretaceous  and  Ter- 
tiary rocks. 

Facts  of  the  above  nature — and  they  could  be  greatly  multi- 
plied— seem  to  point  clearly  to  the  existence  of  some  law  of 
progression,  though  we  certainly  are  not  yet  in  a  position  to 
formulate  this  law,  or  to  indicate  the  precise  manner  in  which 
it  has  operated.  Two  considerations,  also,  must  not  be  over- 
looked. In  the  first  place,  there  are  various  groups,  some  of 
them  highly  organized,  which  make  their  appearance  at  an  ex- 
tremely ancient  date,  but  which  continue  throughout  geological 
time  almost  unchanged,  and  certainly  unprogressive.  Many  of 
these  "  persistent  types "  are  known — such  as  various  of  the 
Foraminifera,  the  Lingulce,  the  Nautili,  &c. ;  and  they  indicate 
that  under  given  conditions,  at  present  unknown  to  us,  it  is 
possible  for  a  life-form  to  subsist  for  an  almost  indefinite  period 
without  any  important  modification  of  its  structure.  In  the 
second  place,  whilst  the  facts  above  mentioned  point  to  some 
general  law  of  progression  of  the  great  zoological  groups,  it 
cannot  be  asserted  that  the  primeval  types  of  any  given  group 
are  necessarily  "lower,"  zoologically  speaking,  than  their 
modern  representatives.  Nor  does  this  seem  to  be  at  all 
necessary  for  the  establishment  of  the  law  in  question.  It 
cannot  be  asserted,  for  example,  that  the  Ganoid  and  Placoid 
Fishes  of  the  Upper  Silurian  are  in  themselves  less  highly 
organized  than  their  existing  representatives;  nor  can  it  even 
be  asserted  that  the  Ganoid  and  Placoid  orders  are  low  groups 
of  the  class  Pisces.  On  the  contrary,  they  are  high  groups; 
but  then  it  must  be  remembered  that  these  are  probably  not 
really  the  first  Fishes,  and  that  if  we  meet  with  Fishes  at  some 
future  time  in  the  Lower  Silurian  or  Cambrian,  these  may 
easily  prove  to  be  representatives  of  the  lower  orders  of  the 
class.  This  question  cannot  be  further  entered  into  here,  as 
its  discussion  could  be  carried  out  to  an  almost  unlimited 
length;  but  whilst  there  are  facts  pointing  both  ways,  it 
appears  that  at  present  we  are  not  justified  in  asserting  that  the 
earlier  types  of  each  group — so  far  as  these  are  known  to  us, 
or  really  are  without  predecessors — are  necessarily  or  invariably 
more  "  degraded "  or  "  embryonic "  in  their  structure  than 
their  more  modern  representatives. 

It  remains  to  consider  very  briefly  how  far  Palaeontology 
supports  the  doctrine  of  "  Evolution, "  as  it  is  called ;  and  this, 


SUCCESSION  OF  LIFE  UPON  THE  GLOBE.        387 

too,  is  a  question  of  almost  infinite  dimensions,  which  can  but 
be  glanced  at  here.  Does  Palaeontology  teach  us  that  the 
almost  innumerable  kinds  of  animals  and  plants  which  we 
known  to  have  successively  flourished  upon  the  earth  in  past 
times  were  produced  separately  and  wholly  independently  of 
each  other,  at  successive  periods  ?  or  does  it  point  to  the 
theory  that  a  large  number  of  these  supposed  distinct  forms 
have  been  in  reality  produced  by  the  slow  modification  of  a 
comparatively  small  number  of  primitive  types  ?  Upon  the 
whole,  it  must  be  unhesitatingly  replied  that  the  evidence  of 
Palaeontology  is  in  favor  of  the  view  that  the  succession  of 
life-forms  upon  the  globe  has  been  to  a  large  extent  regulated 
by  some  orderly  and  constantly-acting  law  of  modification  and 
evolution.  Upon  no  other  theory  can  we  comprehend  how 
the  fauna  of  any  given  formation  is  more  closely  related  to 
that  of  the  formation  next  below  in  the  series,  and  to  that  of 
the  formation  next  above,  than  to  that  of  any  other  series  of 
deposits.  Upon  no  other  view  can  we  comprehend  why  the 
Post-Tertiary  Mammals  of  South  America  should  consist  prin- 
cipally of  Edentates,  Llamas,  Tapirs,  Peccaries,  Platyrhine 
Monkeys,  and  other  forms  now  characterizing  this  continent; 
whilst  those  of  Australia  should  be  wholly  referable  to  the 
order  of  Marsupials.  On  no  other  view  can  we  explain  the 
common  occurrence  of  "  intermediate "  or  "  transitional " 
forms  of  life,  filling  in  the  gaps  between  groups  now  widely 
distinct. 

On  the  other  hand,  there  are  facts  which  point  clearly  to  the 
existence  of  some  law  other  than  that  of  evolution,  and  prob- 
ably of  a  deeper  and  more  far-reaching  character.  Upon  no 
theory  of  evolution  can  we  find  a  satisfactory  explanation  for 
the  constant  introduction  throughout  geological  time  of  new 
forms  of  life,  which  do  not  appear  to  have  been  preceded  by 
pre-existent  allied  types.  The  Graptolites  and  Trilobites  have 
no  known  predecessors,  and  leave  no  known  successors.  The 
Insects  appear  suddenly  in  the  Devonian,  and  the  Arachnides 
and  Myriapods  in  the  Carboniferous,  under  well-differentiated 
and  highly-specialized  types.  The  Dibranchiate  Cephalopods 
appear  with  equal  apparent  suddenness  in  the  older  Mesozoic 
deposits,  and  no  known  type  of  the  Palaeozoic  period  can  be 
pointed  to  as  a  possible  ancestor.  The  Hifipuritida  of  the 
Cretaceous  burst  into  a  varied  life  to  all  appearance  almost 
immediately  after  their  first  introduction  into  existence.  The 
wonderful  Dicotyledonous  flora  of  the  Upper  Cretaceous 


388  HISTORICAL  PALAEONTOLOGY. 

period   similarly   surprises   us   without   any  prophetic   annuncia- 
tion from  the  older  Jurassic. 

Many  other  instances  could  be  given;  but  enough  has  been 
said  to  show  that  there  is  a  good  deal  to  be  said  on  both  sides, 
and  that  the  problem  is  one  environed  with  profound  difficul- 
ties. One  point  only  seems  now  to  be  universally  conceded, 
and  that  is,  that  the  record  of  life  in  past  time  is  not  interrupted 
by  gaps  other  than  those  due  to  the  necessary  imperfections  of 
the  fossiliferous  series,  to  the  fact  that  many  animals  are  in- 
capable of  preservation  in  a  fossil  condition,  or  to  other  causes 
of  a  like  nature.  All  those  who  are  entitled  to  speak  on  this 
head  are  agreed  that  the  introduction  of  new  and  the  destruc- 
tion of  old  species  have  been  slow  and  gradual  processes,  in  no 
sense  of  the  term  "  catastrophistic."  Most  are  also  willing  to 
admit  that  "  Evolution "  has  taken  place  in  the  past,  to  a 
greater  or  less  extent,  and  that  a  greater  or  less  number  of  so- 
called  species  of  fossil  animals  are  really  the  modified  descend- 
ants of  pre-existent  forms.  How  this  process  of  evolution  has 
been  effected,  to  what  extent  it  has  taken  place,  under  what 
conditions  and  laws  it  has  been  carried  out,  and  how  far  it 
may  be  regarded  as  merely  auxiliary  and  supplemental  to  some 
deeper  law  of  change  and  progress,  are  questions  to  which,  in 
spite  of  the  brilliant  generalizations  of  Darwin,  no  satisfactory 
answer  can  as  yet  be  given.  In  the  successful  solution  of  this 
problem — if  soluble  with  the  materials  available  to  our  hands 
— will  lie  the  greatest  triumph  that  Palaeontology  can  hope  to 
attain ;  and  there  is  reason  to  think  that,  thanks  to  the  guiding- 
clue  afforded  by  the  genius  of  the  author  of  the  '  Origin  of 
Species/  we  are  at  least  on  the  road  to  a  sure,  though  it  may 
be  a  far-distant,  victory. 


APPENDIX. 


TABULAR    VIEW    OF    THE    CHIEF    DIVISIONS 
OF  THE  ANIMAL  KINGDOM. 

(Extinct  groups  are  marked  with  an  asterisk.     Groups  not  rep- 
resented at  all  as  fossils  are  marked  with  two  asterisks.) 

INVERTEBRATE  ANIMALS. 

SUB-KINGDOM   I. — PROTOZOA. 

Animal  simple  or  compound ;  body  composed  of  "  sarcode, " 
not  definitely  segmented ;  no  nervous  system ;  and  no  digestive 
apparatus,  beyond  occasionally  a  mouth  and  gullet. 

CLASS  I.  GREGARINID^:.  ** 
CLASS  II.  RHIZOPODA. 

Order  i.  Monera.  ** 

Order  2.  Ama?bea.  ** 

Order  3.  Foraminifera. 

Order  4.  Radiolaria   ( Polycystines,  &c.) 

Order  5.  Spongida  (Sponges). 
CLASS  III.  INFUSORIA.  ** 

SUB-KINGDOM  II. — CCELENTERATA. 

Animal  simple  or  compound;  body-wall  composed  of  two 
principal  layers;  digestive  canal  freely  communicating  with  the 
general  cavity  o'f  the  body ;  no  circulating  organs,  and  no 
nervous  system  or  a  rudimentary  one ;  mouth  surrounded  by 
tentacles,  arranged,  like  the  internal  organs,  in  a  "  radiate "  or 
star-like  manner. 

(389) 


390  APPENDIX. 

CLASS  I.  HYDROZOA. 

Sub-class    i.    Hydroida    ("  Hydroid   Zoophytes").     Ex. 

Freshwater    Polypes,**    Pipe  -  corallines    (Tubularia), 

Sea  -  Firs    (Sertularia). 
Sub-class  2.  Siphonophora**     ("  Oceanic     Hydrozoa"). 

Ex.  Portuguese  Man-of-war   (Physalia). 
Sub-class  3.  Discophora    ("Jelly-fishes").     Only  known 

as  fossils  by  impressions  of  their  stranded  carcasses. 
Sub-class  4.  Luccrnarida    ("  Sea-blubbers  ").      Also  only 

known   as   fossils  by  impressions  left  in   fine-grained 

strata. 
Sub-class  5.  Graptolitidce*   ("  Graptolites  "). 

CLASS  II.  ACTINOZOA. 

Order  i.  Zoantharia.  Ex.  Sea-anemones**  (Actin- 
idce),  Star-corals  (Astr&idtf). 

Order  2,  Alcyonaria.  Ex.  Sea-pens  (Pennatula),  Or- 
gan-pipe Coral  (Tubipora),  Red  Coral  (Corallium). 

Order  3.  Rugosa    ("Rugose  Corals"). 

Order  4.  Ctenophora.**  Ex.  Venus's  Girdle    (Cestum). 


SUB-KINGDOM   III. — ANNULOIDA. 

Animals  in  which  the  digestive  canal  is  completely  shut  off 
from  the  cavity  of  the  body ;  a  distinct  nervous  system ;  a 
system  of  branched  "  water-vessels, "  which  usually  communi- 
cate with  the  exterior.  Body  of  the  adult  often  "  radiate,  "  and 
never  composed  of  a  succession  of  definite  rings. 

CLASS    I.    ECHINODERMATA. 

Order  i.  Crinoidea     ("Sea-lilies").      Ex.     Feather-star 

(Comatula),  Stone-lily  (Encrinus*). 
Order  2.  Blastotdea*    ("  Pentremites  "). 
Order  3.  Cystoidea*    ("Globe-lilies"). 
Order  4.  Ophiuroidea   ("Brittle-stars").  Ex.  Sand-stars 

(Ophiura),  Brittle-stars   (Ophiocoma}. 
Order  5.  Asteroidea    ("Star-fishes").      Ex.    Cross-fish 

(Uraster),  Sun-star  (Solaster}. 
Order  6.  Echinoidea     ("Sea-urchins").      Ex.    Sea-eggs 

(Echinus),  Heart-urchins    (Spatangus). 
Order  7.  Holothuroidea    ("  Sea  -  cucumbers  ").   Ex.  Tre- 

pangs   (Holothuria). 

CLASS  II.  SCOLECIDA**   (Intestinal  Worms,  Wheel  Animalcules, 
&c.) 


SUB-KINGDOM   IV. — ANNULOSA. 

Animal  composed  of  numerous  definite  segments  placed  one 
behind  the  other;  nervous  system  forming  a  knotted  cord  placed 
along  the  lower  (ventral)  surface  of  the  body. 


APPENDIX.  391 

Division  A.  Anarthropoda.     No  jointed  limbs. 

CLASS  I.-GEPHYREA**  ("Spoon-worms"). 

CLASS  II.  ANNELIDA  ("Ringed-worms").  Ex.  Leeches** 
(Hirudinea),  Earthworms**  Oligochceta),  Tube-worms 
(Tubicola),  Sea-worms  and  Sea-centipedes  (Errantia). 

CLASS  III.  CH^TOGNATHA **   ("Arrow-worms"). 

Division  B.  Arthropoda  or  Articulata.  Limbs  jointed  to  the 
body. 

CLASS  I.  CRUSTACEA  ("Crustaceans").  Ex.  Barnacles  and 
Acorn-shells  (Cirripedia),  Water-fleas  (Ostracoda), 
Brine-shrimps  and  Fairy-shrimps  (Phyllopoda),  Trilo- 
bites  *  (Trilobita),  King-crabs  and  Eurypterids  *  (Mer- 
ostomata),  Wood-lice  and  Slaters  (Isopoda),  Sand-hop- 
pers (Amphipoda),  Lobsters,  Shrimps,  Hermit-crabs,  and 
Crabs  (Decapoda). 

CLASS  II.  ARACHNIDA.  Ex.  Mites  (Acarina),  Scorpions  (Pedi- 
palpi),  Spiders  (Araneida). 

CLASS  III.  MYRIAPODA.  Ex.  Centipedes  (Chilopoda),  Millipedes 
and  Galley-worms  (Chilognatha). 

CLASS  IV.  INSECTA  ("Insects").  Ex.  Field-bugs  (Hemiptera)  ; 
Crickets,  Grasshoppers,  &c.  (Orthoptera)  ;  Dragon-flies 
and  May-flies  {Neuroptera}  ;  Gnats  and  House-flies  (Dip- 
tera]  ;  Butterflies  and  Moths  (Lepidoptera}  ;  Bees,  Wasps 
and  Ants  (Hymenoptera)  ;  Beetles  (Coleoptera). 

SUB-KINGDOM    V. — MOLLUSCA. 

Animal  soft-bodied,  generally  with  a  hard  covering  or  shell ; 
no  distinct  segmentation  of  the  body ;  nervous  system  of  scat- 
tered masses.  • 

CLASS  I.  POLYZOA    ("Sea-Mosses").     Ex.    Sea-mats    (Flustra), 

Lace-corals   (Fenestellidte*}. 
CLASS  II.  TUNICATA  **     ("  Tunicaries ")       Ex.     Sea-squirts 

(Ascidia}. 
CLASS  III.  BRACHIOPODA    ("Lamp-shells").     Ex.    Goose-bill 

Lamp-shell  (Lingula}. 
CLASS  IV.  LAMELLIBRANCHIATA      ("Bivalves").       Ex.     Oyster 

(Ostrea},    Mussel    (Mytilus},    Scallop    (Pecten),    Cockle 

(Cardium). 
CLASS  V.  GASTEROPODA    ("Univalves").      Ex.    Whelks    (Bucci- 

num},    Limpets    (Patella),    Sea-slugs**    (Doris),    Land- 
snails  (Helix). 
CLASS   VI.  PTEROPODA    ("Winged   Snails").     Ex   Hyalea,   Cleo- 

dora. 
CLASS  VII.  CEPHALOPODA    ("Cuttle-fishes").     Ex.   Calamary 

(Loligo),    Poulpe     (Octopus),    Paper    Nautilus     (Argon- 

auta),   Pearly   Nautilus    (Nautilus),   Belemnites,  *   Ortho- 

ceratites,  *  Ammonites.  * 


392  APPENDIX. 

VERTEBRATE   ANIMALS. 

SUB-KINGDOM  VI. — VERTEBRATA. 

Body  composed  of  definite  segments  arranged  longitudinally 
one  behind  the  other ;  main  masses  of  the  nervous  system  placed 
dorsally;  a  backbone  or  "vertebral  column"  in  the  majority. 

CLASS  I.  PISCES  ("Fishes").  Ex.  Lancelet  *  *  (Amphioxus}'', 
Lampreys  and  Hag-fishes  (Marsipobranchii  *  *)  ;  Herring, 
Salmon,  Perch,  &c.  (Teleostei  or  "Bony  Fishes");  Gar- 
pike,  Sturgeon,  &c.  (Ganoidei}  ;  Sharks,  Dog-fishes,  Rays, 
&c.  (Elasmobranchii  or  "Placoids"). 

CLASS  II.  AMPHIBIA  ("Amphibians").  Ex.  Labyrinthodontia,* 
Csecilians,  *  *  Newts  and  Salamanders  (Urodela),  Frogs 
and  Toads  (Anoura}. 

CLASS  III.  REPTILIA  ("Reptiles").  Ex.  Deinosauria,*  Ptero- 
sauria,*  Anomodontia,*  Plesiosaurs  (Sauropterygia*), 
Ichthyosaurs  (Ichthyopterygia*),  Tortoises  and  Turtles 
(Chelonia},  Snakes  (Ophidia),  Lizards  (Lacertilia), 
Crocodiles  (Crocodilia}. 

CLASS  IV.  AVES  ("Birds").  Ex.  Toothed  Birds  (Odontor- 
nithes*};  Lizard-tailed  Birds  (Archceopteryx  *)  ;  Ducks, 
Geese,  Gulls,  &c.  (Natatores}  ;  Storks,  Herons,  Snipes, 
Plovers,  &c.  (Grallatores)  ;  Ostrich,  Emeu,  Cassowary, 
Dinornis,  *  ^piornis,  *  &c.  (Cursorcs)  ;  Fowls,  Game 
Birds  and  Doves  (Rasores}  ;  Cuckoos,  Woodpeckers, 
Parrots,  &c.  (Scansores)  ;  Crows,  Starlings,  Finches, 
Humming-birds,  Swallows,  &c.  (Insessores)  ;  Owls, 
Hawks,  Eagles,  Vultures  (Raptores}. 

CLASS  V.  MAMMALIA  ("Quadrupeds").  Ex.  Duck-mole  and 
Spiny  Ant-eater  (Monotremata  *  *)  ;  Kangaroos,  Phal- 
•  angers,  Opossums,  Tasmanian  Devil,  &c.  (Marsupialia)  ; 
Sloths,  Ant-eaters,  Armadillos  (Edentata}  ;  Manatees 
and  Dugongs  (Sirenid)  ;  Whales,  Dolphins,  Porpoises 
(Cetacea)  ;  Rhinoceros,  Tapir,  Horses,  Hippopotamus, 
Pigs,  Camels  and  Llamas,  Giraffes,  Deer,  Antelopes, 
Sheep,  Goats,  Oxen  (Ungulata}  ;  Hyrax  (Hyracoidea  *  *)  ; 
Elephants,  Mastodon,  *  Deinotherium  *  (Proboscidea}  ; 
Seals,  Walrus,  Bears,  Dogs,  Wolves,  Cats,  Lions,  Tigers, 
&c.  (Carnivora}  ;  Hares,  Rabbits,  Porcupines,  Beavers, 
Rats,  Mice,  Lemmings  Squirrels,  Marmots,  &c.  (Rodeii- 
tia}  ;  Bats  (Cheiroptera}  ;  Moles,  Shrew-mice,  Hedge- 
hogs (Insectivora}  ;  Lemurs,  Spider-monkeys,  Macaques, 
Baboons,  Apes  (Quadrumana}  ;  Man  (Bimana). 


GLOSSARY 


ABDOMEN  (Lat.  abdo,  I  conceal).  The  posterior  cavity  of  the 
body,  containing  the  intestines  and  others  of  the  viscera.  In 
many  Invertebrates  there  is  no  separation  of  the  body-cavity 
into  thorax  and  abdomen,  and  it  is  only  in  the  higher  Annulosa 
that  a  distinct  abdomen  can  be  said  to  exist. 

ABERRANT  (Lat.  aberro,  I  wander  away).  Departing  from  the 
regular  type. 

ABNORMAL  (Lat.  ab,  from;  norma,  a  rule).  Irregular;  deviating 
from  the  ordinary  standard. 

ACRODUS  (Gr.  akros,  high;  odous,  tooth).  A  genus  of  the  Ces- 
traciont  fishes;  so-called  from  the  elevated  teeth. 

ACROGENS  (Gr.  akros,  high;  gennao,  I  produce).  Plants  which 
increase  in  height  by  additions  made  to  the  summit  of  the 
stem  by  the  union  of  the  bases  of  the  leaves. 

ACROTRETA  (Gr.  akros,  high;  trStos,  pierced).  A  genus  of 
Brachiopods,  so-called  from  the  presence  of  a  foramen  at 
the  summit  of  the  shell. 

ACTINOCRINUS  (Gr!  aktin,  a  ray;  krinon,  a  lily).  A  genus  of 
Crinoids. 

ACTINOZOA  (Gr.  aktin,  a  ray;  and  zo'on,  an  animal).  That 
division  of  the  Ccelenterata  of  which  the  Sea-anemones  may  be 
taken  as  the  type. 

yEGLiNA   (jEgli,  a  sea-nymph).     A  genus  of  Trilobites. 

^PIORNIS  (Gr.  aipus,  huge;  ornis,  bird).  A  genus  of  gigantic 
Cursorial  birds. 

AGNOSTUS  (Gr.  a,  not;  gignosko,  I  know).  A  genus  of  Trilo- 
bites. 

ALCES  (Lat.  dices,  elk).    The  European  Elk  or  Moose. 

ALECTO  (the  proper  name  of  one  of  the  Furies).  A  genus  of 
Polyzoa. 

ALETHOPTERIS  (Gr.  alZthZs,  true;  pteris,  fern).  A  genus  of 
Ferns. 

ALGJE  (Lat.  alga,  a  marine  plant).  The  order  of  plants  com- 
prising the  Sea-weeds  and  many  fresh-water  plants. 

ALVEOLUS  (Lat.  alvus,  belly).  Applied  to  the  sockets  of  the 
teeth. 

AMBLYPTERUS  (Gr.  amblus,  blunt;  pteron,  fin).  An  order  of 
Ganoid  Fishes. 

(393) 


394  GLOSSARY 

AMBONYCHIA  (Gr.  ambon,  a  boss;  onux,  claw).  A  genus  of 
Palaeozoic  Bivalves. 

AMBULACRA  (Lat.  ambulacrum,  a  place  for  walking).  The  per- 
forated spaces  or  "  avenues  "  through  which  are  protruded  the 
tube-feet,  by  means  of  which  locomotion  is  effected  in  the 
Echinodermata. 

AMMONiTiDyE.  A  family  of  Tetrabranchiate  Cephalopods,  so- 
called  from  the  resemblance  of  the  shell  of  the  type-genus, 
Ammonites,  to  the  horns  of  the  Egyptian  God,  Jupiter-Am- 
mon. 

AMORPHOZOA  (Gr.  a,  without;  morphe,  shape;  soon,  animal).  A 
name  sometimes  used  to  designate  the  Sponges. 

AMPHIBIA  (Gr.  amphl,  both;  bios,  life).  The  Frogs,  Newts, 
and  the  like,  which  have  gills  when  young,  but  can  always 
breathe  air  directly  when  adult. 

AMPHICYON  (Gr.  am  phi,  both — implying  doubt;  kuDn,  dog).  An 
extinct  genus  of  Carnivora. 

AMPHILESTES  (Gr.  amphl,  both;  lestZs,  a  thief).  A  genus  of 
Jurassic  Mammals. 

AMPHISPONGIA  (Gr.  amphi,  both;  spoggos,  sponge).  A  genus 
of  Silurian  sponges. 

AMPHISTEGINA  (Gr.  dmphi,  both;  stege',  roof).  A  genus  of 
Foraminifera. 

AMPHITHERIUM  (Gr.  amphi,  both;  therion,  beast).  A  genus  of 
Jurassic  Mammals. 

AMPHITRAGULUS  (Gr.  amphi,  both;  dim.  of  tragos,  goat).  An 
extinct  genus  related  to  the  living  Musk-deer. 

AMPLEXUS   (Lat.  an  embrace).     A  genus  of  Rugose  Corals. 

AMPYX  (Gr.  ampux,  a  wreath  or  wheel).  A  genus  of  Trilo- 
bites. 

ANARTHROPODA  (Gr.  a,  without;  arthros,  a  joint;  pous,  foot). 
That  division  of  Annulose  animals  in  which  there  are  no 
articulated  appendages. 

ANCHITHERIUM  (Gr.  agchi,  near;  therion,  beast).  An  extinct 
genus  of  Mammals. 

ANCYLOCERAS  (Gr.  agkulos,  crooked;  ceras,  horn).  A  genus  of 
Ammonitidce. 

ANCYLOTHERIUM  (Gr.  agkulos,  crooked;  therion,  beast).  An 
extinct  genus  of  Edentate  Mammals. 

ANDRIAS  (Gr.  andrias,  image  of  man).  An  extinct  genus  of 
tailed  Amphibians. 

ANGIOSPERMS  (Gr.  angeion,  a  vessel;  sperma,  seed).  Plants 
which  have  their  seeds  enclosed  in  a  seed-vessel. 

ANNELIDA  (a  Gallicised  form  of  Annulata}.  The  Ringed 
Worms,  which  form  one  of  the  divisions  of  the  Anarthropoda. 

ANNULARIA  (Lat.  annulus,  a  ring).  A  genus  of  Palaeozoic 
plants,  with  leaves  in  whorls. 

ANNULOSA  (Lat.  annulus).  The  sub-kingdom  comprising  the 
Anarthropoda  and  the  Arthropoda  or  Articulata,  in  all  of 
which  the  body  is  more  or  less  evidently  composed  of  a  suc- 
cession of  rings. 

ANOMODONTIA  (Gr.  anomos,  irregular;  odous,  tooth).  An  ex- 
tinct order  of  Reptiles,  often  called  Dicynodontia. 


GLOSSARY  395 

ANOMURA  (Gr.  anomos,  irregular;  oura,  tail).  A  tribe  of  De- 
capod Crustacea,  of  which  the  Hermit-crab  is  the  type. 

ANOPLOTHERID;E  (Gr.  anoplos,  unarmed;  ther,  beast).  A  family 
of  Tertiary  Ungulates. 

ANOURA  (Gr.  a,  without;  oura,  tail).  The  order  of  Amphibia 
comprising  the  Frogs  and  Toads,  in  which  the  adult  is  desti- 
tute of  a  tail.  Often  called  Batrachia. 

ANTENNA  (Lat.  antenna,  a  yard-arm).  The  jointed  horns  or 
feelers  possessed  by  the  majority  of  the  Articulata. 

ANTENNULES  (dim.  of  Antenna}.  Applied  to  the  smaller  pair 
of  antennae  in  the  Crustacea. 

ANTHRACOSAURUS  (Gr.  anthrax,  coal;  saura,  lizard).  A  genus 
of  Labyrinthodont  Amphibians. 

ANTHRAPAUEMON  (Gr.  anthrax,  coal;  palcemfin,  a  prawn — orig- 
inally a  proper  name).  A  genus  of  long-tailed  Crustaceans 
from  the  Coal-measures. 

ANTLERS.  Properly  the  branches  of  the  horns  of  the  Deer  tribe 
(Cervidce},  but  generally  applied  to  the  entire  horns. 

APIOCRINID^:  (Gr.  apion,  a  pear;  krinon,  lily).  A  family  of 
Crinoids — the  "  Pear-encrinites.  " 

APTERYX  (Gr.  a,  without;  pterux,  a  wing).  A  wingless  bird 
of  New  Zealand,  belonging  to  the  order  Cursores. 

AQUEOUS    (Lat.  aqua,  water).     Formed  in  or  by  water. 

ARACHNIDA  (Gr.  arachne,  a  spider).  A  class  of  the  Articulata, 
comprising  Spiders,  Scorpions,  and  allied  animals. 

ARBORESCENT,     Branched  like  a  tree. 

ARCH^EOCIDARIS  (Gr.  archaios,  ancient;  Lat.  cidaris,  a  diadem). 
A  Palaeozoic  genus  of  Sea-urchins,  related  to  the  existing 
Cidaris. 

ARCH.EO'CYATHUS  (Gr.  archaios,  ancient;  kuathos,  cup).  A 
genus  of  Palaeozoic  fossils  allied  to  the  Sponges. 

ARCHyEOFTERYx  (Gr.  archaios,  ancient;  pterux,  a  wing).  The 
singular  fossil  bird  which  alone  constitutes  the  order  of  the 
Saurura. 

ARCTOCYON  (Gr.  arctos,  bear;  kuon,  dog).  An  extinct  genus 
of  Carnivora. 

ARENACEOUS.     Sandy,  or  composed  of  grains  of  sand. 

ARENICOLITES  (Lat.  arena,  sand;  colo,  I  inhabit).  A  genus 
founded  on  burrows  supposed  to  be  formed  by  worms  re- 
sembling the  living  Lobworms  (Arenicola). 

ARTICULATA  (Lat.  articulus,  a  joint).  A  division  of  the  animal 
kingdom,  comprising  Insects,  Centipedes,  Spiders  and  Crus- 
taceans, characterized  by  the  possession  of  jointed  bodies  or 
jointed  limbs.  The  term  Arthropoda  is  now  more  usually 
employed. 

ARTIODACTYLA  (Gr.  artios,  even;  daktulos,  a  finger  or  toe).  A 
division  of  the  hoofed  quadrupeds  (Ungulata)  in  which  each 
foot  has  an  even  number  of  toes  (two  or  four). 

ASAPHUS   (Gr.  asaphZs,  obscure).     A  genus  of  Trilobites. 

ASCOCERAS  (Gr.  askos,  a  leather  bottle;  keras,  horn).  A  genus 
of  Tetrabranchiate  Cephalopods. 

ASIPHONATE.  Not  possessing  a  respiratory  tube  or  siphon.  (Ap- 
plied to  a  division  of  the  Lamellibranchiate  Molluscs.) 


396  GLOSSARY 

ASTEROID  (Gr.  aster,  a  star;  and  eidos,  form).  Star-shaped,  or 
possessing  radiating  lobes  or  rays  like  a  star-fish. 

ASTEROIDEA.  An  order  of  Echinodermata,  comprising  the  Star- 
fishes, characterized  by  their  rayed  form. 

ASTEROPHYLLITES  (Gr.  aster,  a  star;  phullon,  leaf).  A  genus  of 
Palaeozoic  plants,  with  leaves  in  whorls. 

ASTRJEIVJE  (Gr.  Astros,  a  proper  name).  The  family  of  the 
Star-corals. 

ASTYLOSPONGIA  (Gr.  a,  without;  stulos,  a  column;  spoggos,  a 
sponge).  A  genus  of  Silurian  Sponges. 

ATHYRIS  (Gr.  a,  without;  thura,  door).    A  genus  of  Brachiopods. 

ATRYPA  (Gr.  a,  without;  trupa,  a  hole).    A  genus  of  Brachiopods. 

AVES   (Lat.  avis,  a  bird).     The  class  of  the  Birds. 

AVICULA  (Lat.  a  little  bird).  The  genus  of  Bivalve  Molluscs 
comprising  the  Pearl-oysters. 

AXOPHYLLUM  (Gr.  axon,  a  pivot;  phullon,  a  leaf).  A  genus  of 
Rugose  Corals. 

Azoic  (Gr.  a,  without;  zoe,  life).  Destitute  of  traces  of  living 
beings. 


B 

BACULITES  (Lat.  baculum,  a  staff).  A  genus  of  the  Ammoni- 
tid<z. 

BAL^NA  (Lat.  a  whale).     The  genus  of  the  Whalebone  Whales. 

BALANID.E  (Gr.  balanos,  an  acorn).  A  family  of  sessile  Cirri- 
pedes,  commonly  called  "  Acorn-shells.  " 

BATRACHIA  (Gr.  batrachos,  a  frog).  Often  loosely  applied  to 
any  of  the  Amphibia,  but  sometimes  restricted  to  the  Am- 
phibians as  a  class,  or  to  the  single  order  of  the  Anoura, 

BELEMNITHLE  (Gr.  belemnon,  a  dart).  An  extinct  group  of 
Dibranchiate  Cephalopods,  comprising  the  Belemnites  and 
their  allies. 

BELEMNOTEUTHIS  (Gr.  belemnon,  a  dart;  teuthis,  a  cuttle-fish). 
A  genus  allied  to  the  Belemnites  proper. 

BELINURUS  (Gr.  belos,  a  dart;  our  a,  tail).  A  genus  of  fossil 
King-crabs. 

BELLEROPHON  (Gr.  proper  name).  A  genus  of  oceanic  Uni- 
valves (Heteropoda}. 

BELOTEUTHIS  (Gr.  belos,  a  dart;  teuthis,  a  cuttle-fish).  An  ex- 
tinct genus  of  Dibranchiate  Cephalopods. 

BEYRICHIA  (named  after  Prof.  Beyrich).  A  genus  of  Ostra- 
code  Crustaceans. 

BILATERAL.     Having  two  symmetrical  sides. 

BIMANA  (Lat.  bis,  twice;  manus,  a  hand).  The  order  of  Mam- 
malia comprising  man  alone. 

BIPEDAL   (Lat.   bis,  twice;  pes,  foot).     Walking  upon  two  legs. 

BIVALVE  (Lat.  bis,  twice  valves,  folding-doors).  Composed  of 
two  plates  or  valves;  applied  to  the  shell  of  the  Lamellibran- 
chiata  and  Brachiopoda,  and  to  the  carapace  of  certain  Crus- 
tacea. 

BLASTOIDEA  (Gr.  blastos,  a  bud;  and  eidos,  form).  An  extinct 
order  of  Echinodermata,  often  called  Pentremites. 


GLOSSARY  397 

BRACHIOPODA  (Gr.  brachion,  an  arm;  pous,  the  foot).  A  class 
of  the  Molluscoida,  often  called  "  Lamp-shells,  "  characterized 
by  possessing  two  fleshy  arms  continued  from  the  sides  of 
the  mouth. 

BRACHYURA  (Gr.  brachus,  short;  oura,  tail).  A  tribe  of  the 
Decapod  Crustaceans  with  short  tails  (/.  e.,  the  Crabs.) 

BRADYPODID^E  (Gr.  bradus,  slow;  podes,  feet).  The  family  of 
Edentata  comprising  the  Sloths. 

BRANCHIA  (Gr.  bragchia,  the  gill  of  a  fish).  A  respiratory 
organ  adapted  to  breathe  air  dissolved  in  water. 

BRANCHIATE.     Possessing  gills  or  branchiae. 

BRONTEUS  (Gr.  bronte",  thunder — an  epithet  of  Jupiter  the  Thun- 
derer). A  genus  of  Trilobites. 

BRONTOTHERIUM  (Gr.  brontf,  thunder;  therion,  beast).  An  ex- 
tinct genus  of  Ungulate  Quadrupeds. 

BRONTOZOUM  (Gr.  bronte*,  thunder;  soon,  animal).  A  genus 
founded  on  the  largest  footprints  of  the  Triassic  Sandstones 
of  Connecticut. 

BUCCTNUM  (Lat.  buccinum,  a  trumpet).  The  genus  of  Uni- 
valves comprising  the  Whelks. 


CAINOZOIC     (See  Kainozoic.) 

CALAMITES    (Lat.  calamus,  a  reed).     Extinct  plants  with  reed- 
like    stems,    believed    to    be    gigantic    representatives    of    the 

Equisetacece. 

CALCAREOUS   (Lat  calx,  lime).     Composed  of  carbonate  of  lime. 
CALICE.     The  little  cup  in  which  the  polype  of  a  coralligenous 

Zoophyte   (Act'mozo'dn)  is  contained. 

CALYMENE   (Gr.  kalumene',  concealed).     A  genus  of  Trilobites. 
CALYX    (Lat.    a   cup).     Applied  to   the   cup-shaped   body   of    a 

Crinoid   (Echinodermata}. 
CAMAROPHORIA    (Gr.   kamara,  a  chamber;   phero,   I   carry).     A 

genus  of  Brachiopods. 
CAMELOPARDALID^:   (Lat.  camelus,  a  camel;  pardalis,  a  panther). 

The  family  of  the  Giraffes. 
CANINE    (Lat.   canis,   a  dog).     The  eye-tooth  of   Mammals,  or 

the  tooth  which  is  placed  at  or  close  to  the  praemaxillary  suture 

in  the  upper  jaw,  and  the  corresponding  tooth  in  the  lower 

jaw. 
CARAPACE.     A  protective  shield.     Applied  to  the  upper  shell  of 

Crabs,  Lobsters,  and  many  other   Crustacea.     Also  the  upper 

half  of  the  immovable  case  in  which  the  body  of  a  Chelonian 

is   protected. 
CARCHARODON    (Gr.   karcharos,  rough;   odous,  tooth).     A  genus 

of  Sharks. 
CARDIOCARPON   (Gr.  kardia,  the  heart;  karfios,  fruit).     A  genus 

of  fossil  fruit  from  the  Coal-measures. 
CARDIUM     (Gr.    kardia,    the    heart).      The    genus    of     Bivalve 

Molluscs    comprising    the    Cockles.      Cardinia,    Cardiola,    and 

Cardita  have  the  same  derivation. 
CARNIVORA  (Lat.  caro,  flesh;  voro,  I  devour).     An  order  of  the 

Mammalia.     The  "  Beasts  of  Prey.  " 


398  GLOSSARY. 

CARNIVOROUS  (Lat.  caro,  flesh;  voro,  I  devour).  Feeding  upon 
flesh. 

CARYOCARIS  (Gr.  karua,  a  nut;  karis,  a  shrimp).  A  genus  of 
Phyllopod  Crustaceans. 

CARYOCRINUS  (Gr.  karua,  a  nut;  krinon,  a  lily).  A  genus  of 
Cystideans. 

CAUDAL   (Lat.  cauda,  the  tail).     Belonging  to  the  tail. 

CAVICORNIA  (Lat.  cavus,  hollow;  cornu,  a  horn).  The  "hollow- 
horned  "  Ruminants,  in  which  the  horn  consists  of  a  central 
bony  "  horn-core "  surrounded  by  a  horny  sheath. 

CENTRUM  (Gr.  kentron,  the  point  round  which  a  circle  is 
described  by  a  pair  of  compasses).  The  central  portion  or 
"  body  "  of  a  vertebra. 

CEPHALASPIDVE  (Gr.  kephale,  head;  aspis,  shield).  A  family  of 
fossil  fishes. 

CEPHALIC   (Gr.  kephale,  head).     Belonging  to  the  head. 

CEPHALOPODA  (Gr.  kephale;  and  podes,  feet).  A  class  of  the 
Mollusca,  comprising  the  Cuttle-fishes  and  their  allies,  in 
which  there  is  a  series  of  arms  ranged  round  the  head. 

CERATIOCARIS  (Gr.  keras,  a  horn;  karis,  a  shrimp).  A  genus  pf 
Phyllopod  Crustaceans. 

CERATITES  (Gr.  keras,  a  horn).     A  genus  of  Ammonitidce. 

CERATODUS  (Gr.  keras,  a  horn;  odous,  tooth).  A  genus  of 
Dipnoous  fishes. 

CERVICAL  (Lat.  cervix,  the  neck).  Connected  with  or  belong- 
ing to  the  region  of  the  neck. 

CERVID^E   (Lat.  cervus,  a  stag).     The  family  of  the  deer. 

CESTRAPHORI  (Gr.  kestra,  a  weapon;  phero,  I  carry).  The  group 
of  the  "  Cestraciont  Fishes, "  represented  at  the  present  day 
by  the  Port-Jackson  Shark ;  so-called  from  their  defensive 
spines. 

CETACEA  (Gr.  ketos,  a  whale).  The  order  of  Mammals  com- 
prising the  Whales  and  the  Dolphins. 

CETIOSAURUS  (Gr.  ketos,  whale;  saura,  lizard).  A  genus  of 
Deinosaurian  Reptiles. 

CHEIROPTERA  (Gr.  cheir,  hand;  pteron,  wing).  The  Mammalian 
order  of  the  Bats. 

CHEIROTHERIUM  (Gr.  cheir,  hand;  thSrion,  beast).  The  generic 
name  applied  originally  to  the  hand-shaped  footprints  of 
Labyrinthodonts. 

CHEIRURUS  (Gr.  cheir,  hand;  oura,  tail).  A  genus  of  Trilo- 
bites. 

CHELONIA  (Gr.  chelone',  a  tortoise).  The  Reptilian  order  of 
the  Tortoises  and  Turtles. 

CHONETES  (Gr.  chdne"  or  chDane',  a  chamber  or  box).  A  genus 
of  Brachiopods. 

CIDARIS   (Lat.  a  diadem).     A  genus  of  Sea-urchins. 

CLADODUS  (Gr.  klados,  branch;  odous,  tooth).  A  genus  of 
Fishes. 

CLATHROPORA  (Lat.  clathri,  a  trellis;  porus,  a  pore).  A  genus 
of  Lace-corals  (Poly zoo). 

CLISIOPHYLLUM  (Gr.  klision,  a  hut;  phullon,  leaf).  A  genus 
of  Rugose  Corals. 


GLOSSARY.  399 

CLYMENIA  (Clumene,  a  proper  name).  A  genus  of  Tetra- 
branchiate  Cephalopods. 

COCCOSTEUS  (Gr.  kokkos,  berry;  osteon,  bone).  A  genus  of 
Ganoid  Fishes. 

COCHLIODUS  (Gr.  kochlion,  a  snail-shell;  odous,  tooth).  A  genus 
of  Cestraciont  Fishes. 

COELENTERATA  (Gr.  koilos,  hollow ;  enteron,  the  bowel).  The 
sub-kingdom  which  comprises  the  Hydrosoa  and  Actinozoa, 
Proposed  by  Frey  and  Leuckhart  in  place  of  the  old  term 
Radiata,  which  included  other  animals  as  well. 

COLEOPTERA  ( Gr.  koleos,  a  sheath;  pteron,  wing).  The  order 
of  Insects  (Beetles)  in  which  the  anterior  pair  of  wings  are 
hardened,  and  serve  as  protective  cases  for  the  posterior  pair 
of  membranous  wings. 

COLOSSOCHELYS  (Gr.  kolossos,  a  gigantic  statue;  chelus,  a  tor- 
toise). A  huge  extinct  Land-tortoise. 

COMATULA  (Gr.  koma,  the  hair).  The  Feather-star,  so-called 
in  allusion  to  its  tress-like  arms. 

CONDYLE  (Gr.  kondulos,  a  knuckle).  The  surface  by  which  one 
bone  articulates  with  another.  Applied  especially  to  the 
articular  surface  or  surfaces  by  which  the  skull  articulates 
with  the  vertebral  column. 

CONIFERS  (Lat.  conus,  a  cone;  jero,  I  carry).  The  order  of 
the  Firs,  Pines  and  their  allies,  in  which  the  fruit  is  generally 
a  "  cone  "  or  "  fir-apple.  " 

CONULARIA  (Lat.  conulus,  a  little  cone).  An  extinct  genus  of 
Pteropods. 

COPROLITES  (Gr.  kopros,  dung;  lithos,  stone).  Properly  applied 
to  the  fossilized  excrements  of  animals ;  but  often  employed 
to  designate  phosphatic  concretions  which  are  not  of  this 
nature. 

CORALLITE.  The  corallum  secreted  by  an  Actinozo'dn  which  con- 
sists of  a  single  polype ;  or  the  portion  of  a  composite  coral- 
lum which  belongs  to,  and  is  secreted  by,  an  individual  polype. 

CORALLUM  (from  the  Latin  for' Red  Coral).  The  hard  structures 
deposited  in,  or  by,  the  tissues  of  an  Actinozo'on — commonly 
called  a  "  coral.  " 

CORIACEOUS  (Lat.  corium,  hide).    Leathery. 

CORYPHODON  (Gr.  korus,  helmet;  odous,  tooth).  An  extinct 
genus  of  Mammals,  allied  to  the  Tanirs. 

CRANIUM  (Gr.  kranion,  the  skull).  The  bony  or  cartilaginous 
case  in  which  the  brain  is  contained. 

CRETACEOUS  (Lat.  creta,  chalk).  The  formation  which  in 
Europe  contains  white  chalk  as  one  of  its  most  conspicuous 
members. 

CRINOIDEA  (Gr.  krinon,  a  lily;  eidos,  form).  An  order  of 
Echinodermata,  comprising  forms  which  are  usually  stalked, 
and  sometimes  resemble  lilies  in  shape. 

CRIOCERAS  (Gr.  krios,  a  ram;  keras,  a  horn).  A  genus  of  Am- 
monitidc?. 

CROCODILIA  (Gr.  krokodeilos,  a  crocodile).    An  order  of  Reptiles. 

CROSSOPTERYGID^:  (Gr.  krossotos,  a  fringe;  pterux,  a  fin).  A 
sub-order  of  Ganoids  in  which  the  paired  fins  possess  a 
central  lobe. 


400  GLOSSARY. 

CRUSTACEA  (Lat.  crusta,  a  crust).    A  class  of  Articulate  animals, 

comprising    Crabs,    Lobsters,    etc.,    characterized    by    trie    pos- 
session of  a  hard  shell  or  crust,  which  they  cast  periodically. 
CRYPTOGAMS    (Gr.    kruptos,    concealed;    games,    marriage).      A 

division  of   plants   in   which  the   organs   of   reproduction   are 

obscure  and  there  are  no  true  flowers. 
CTENACANTHUS  (Gr.  kteis,  a  comb;  akantha,  a  thorn).    A  genus 

of  fossil  fishes,  named  from  its  fin-spines. 
CTENOID    (Gr.   kteis,   a   comb;    eidos,   form).     Applied  to   those 

scales  of  fishes  the  hinder  margins  of  which  are  fringed  with 

spines  or  comb-like  projections. 
CURSORES    (Lat.  curro,  I  run).     An  order  of  Aves,  comprising 

birds  destitute  of  the  power  of  flight,  but  formed  for  running 

vigorously  (e.  g.,  the  Ostrich  and  Emeu). 

CUSPIDATE.    Furnished  with  small  pointed  eminences  or  "  cusps.  " 
CYATHOCRINUS   (Gr.  kuathos,  a  cup;  krinon,  a  lily).     A  genus 

of  Crinoids. 
CYATHOPHYLLUM  (Gr.  kuathos,  a  cup;  phullon,  a  leaf).    A  genus 

of  Rugose  Corals. 
CYCLOID   (Gr.  kuklos,  a  circle;  eidos,  form).     Applied  to  those 

scales  of   fishes  which  have  a  regularly  circular  or  elliptical 

outline  with  an  even  margin. 
CYCLOPHTHALMUS    (Gr.    kuklos,   a   circle;    opthalmos,   eye).     A 

genus  of  fossil  Scorpions. 
CYCLOSTOMI   (Gr.  kuklos,  and  stoma,  mouth).     Sometimes  used 

to  designate  the  Hag-fishes  and  Lampreys,  forming  the  order 

Marsipobranchii. 
CYPR^A  (a  name  of  Venus).     The  genus  of  Univalve  Molluscs 

comprising  the  Cowries. 
CYRTOCERAS    (Gr.    kurtos,  crooked;    keras,  horn).     A  genus   of 

Tetrabranchiate   Cephalopods. 
CYSTIPHYLLUM  (Gr.  kustis,  a  bladder;  phullon,  a  leaf).   A  genus 

of  Rugose  Corals. 
CYSTOIDEA    (Gr.  kustis,  a  bladder;   eidos,  form).     The  "  Globe- 

crinoids, "  an  extinct  order  of  Echinodermata. 


D 

DADOXYLON  (Gr.  dadion,  a  torch;  xulon,  wood).  An  extinct 
genus  of  Coniferous  trees. 

DECAPODA  (Gr.  deka,  ten;  podes,  feet).  The  division  of 
Crustacea  which  have  ten  feet;  also  the  family  of  Cuttle- 
fishes, in  which  there  are  ten  arms  or  cephalic  processes. 

DECIDUOUS  (Lat.  decido,  I  fall  off).  Applied  to  parts  which 
fall  off  or  are  shed  during  the  life  of  the  animal. 

DEINOSAURIA  (Gr.  deinos,  terrible;  saura,  lizard).  An  extinct 
order  of  Reptiles. 

DEINOTHERIUM  (Gr.  deinos,  terrible;  therion,  beast).  An  extinct 
genus  of  Proboscidean  Mammals. 

DENDROGRAPTUS  (Gr.  dendron,  tree;  grapho,  I  write).  A  genus 
of  Graptolites. 

DESMIDUE.  Minute  fresh-water  plants,  of  a  green  color,  with- 
out a  siliceous  epidermis. 


GLOSSARY.  401 

DIATOMACE^    (Gr.    diatemno,   I    sever).      An    order   of   minute 

plants   which   are  provided   with   siliceous   envelopes. 
DIBRANCHIATA    (Gr.   dis,  twice ;   bragchia,  gill).     The   order  of 

Cephalopoda  (comprising  the  Cuttle-fishes,  etc.,)  in  which  only 

two  gills  are  present. 
DICERAS    (Gr.   dis,   twice;    keras,   horn).     An   extinct  genus   of 

Bivalve   Molluscs. 
DICTYONEMA    (Gr.   diktuon,  a  net;   nema,  thread).     An  extinct 

genus  of  Polyzoa  (?). 
DICYNODONTIA    (Gr.  dis,  twice;   kuon,  dog;   odous,  tooth).     An 

extinct  order  of  Reptiles. 
DIDYMOGRAPTUS  (Gr.  didumos,  twin;  grapho,  I  write).    A  genus 

of  Graptolites. 
DIMORPHODON  (Gr.  dis,  twice;  morphe,  shape;  odous,  tooth).    A 

genus  of  Pterosaurian  Reptiles. 
DINICHTHYS    (Gr.   deinos,  terrible;    ichthus,   fish).     An   extinct 

genus  of  Fishes. 
DINOCERAS  (Gr.  deinos,  terrible;  keras,  horn).    An  extinct  genus 

of  Mammals. 
DINOPHIS  (Gr.  deinos,  terrible;  ophis,  snake).    An  extinct  genus 

of   Snakes. 
DINORNIS   (Gr.  deinos,  terrible;  ornis,  bird).     An  extinct  genus 

of  Birds. 
DIPLOGRAPTUS    (Gr.  diplos,  double;  grapho,  I  write).     A  genus 

of  Graptolites. 

DIPNOI  (Gr.  dis,  twice;  pnoe',  breath).    An  order  of  Fishes,  com- 
prising the   Mud-fishes,   so-called  in   allusion   to   their   double 

mode  of  respiration. 
DIPROTODON  (Gr.  dis,  twice;  protos,  first;  odous,  tooth).    A  genus 

of  extinct  Marsupials. 
DIPTERA    (Gr.   dis,  twice;  pterpn,  wing).     An  order  of   Insects 

characterized  by  the  possession  of  two  wings. 
DISCOID  (Gr.  diskos,  a  quoit;  eidos,  form).     Shaped  like  a  round 

plate  or  quoit. 

DOLOMITE  (named  after  M.  Dolomieu).     Magnesian  limestone. 
DORSAL  (Lat.  dor  sum,  the  back).    Connected  with  or  placed  upon 

the  back. 
DROMATHERIUM  (Gr.  dromaios,  nimble;  thZrion,  beast).   A  genus 

of  Triassic  Mammals. 
DRYOPITHECUS  (Gr.  drus,  an  oak;  pithekos,  an  ape).    An  extinct 

genus  of  Monkeys. 


ECHINODERMATA  (Gr.  echinos ;  and  derma,  skin).  A  class  of 
animals  comprising  the  Sea-urchins,  Star-fishes  and  others, 
most  of  which  have  spiny  skins. 

ECHINOIDEA  (Gr.  echinos;  and  eidos,  form).  An  order  of 
Echinodermata,  comprising  the  Sea-urchins. 

EDENTATA  (Lat.  e,  without;  dens,  tooth).  An  order  of  Mam- 
malia often  called  Bruta. 

EDENTULOUS.     Toothless,  without  any  dental  apparatus.    Applied 
to  the  mouth  of  any  animal,  or  to  the  hinge  of  the  Bivalve 
Molluscs. 
26 


402  GLOSSARY. 

ELASMOBRANCHII  (Gr.  elasma,.a  plate;  bragchia,  gill).    An  order 

of  Fishes,  including  the  Sharks  and  Rays. 
ENALIOSAURIA   (Gr.  enalios,  marine;  saura,  lizard).     Sometimes 

employed  as  a  common  term  to  designate  the  extinct  Reptilian 

orders  of  the  Ichthyosauria  and  Plesiosauria. 
EOCENE    (Gr.   eos,  dawn;    kainos,  new  or   recent).     The   lowest 

division   of   the   Tertiary   rocks,   in   which   species   of   existing 

shells  are  to  a  small  extent  represented. 

EOPHYTON  (Gr.  eos,  dawn;  phuton,  a  plant).     A  genus  of  Cam- 
brian fossils,  supposed  to  be  of  a  vegetable  nature. 
Eozo'dN   (Gr.  eos,  dawn;  zoon,  animal).     A  genus  of  chambered 

calcareous  organisms  found  in  the  Laurentian  and  Huronian 

formations. 
EQUILATERAL  (Lat.  cequus,  equal;  latus,  side).     Having  its  sides 

equal.      Usually    applied    to    the    shells    of  the    Brachiopoda. 

When    applied    to    the    spiral    shells    of    the    Foraminifera,    it 

means  that  all  the  convolutions  of  the  shell  lie  in  the  same 

plane. 
EQUISETACE^E    (Lat.   equus,   horse;   seta,  bristle).     A   group   of 

Cryptogamous  plants,   commonly  known   as   "  Horse-tails. " 
EQUIVALVE   (Lat.  (equus,  equal;  valvce,  folding-doors).     Applied 

to  shells  which  are  composed  of  two  equal  pieces  or  valves. 
ERRANTIA   (Lat.  erro,  I  wander).     An  order  of  Annelida,  often 

called    Nereidea,     distinguished'  by    their     great    locomotive 

powers. 
EUOMPHALUS  (Gr.  eu,  well;  omphalos,  navel).    An  extinct  genus 

of  Univalve  Molluscs. 

EURYPTERIDA  (Gr.  eurus,  broad ;  pteron,  wing).     An  extinct  sub- 
order of  Crustacea. 
EXOGYRA    (Gr.   exo,  outside;   guros,  circle).     An  extinct  genus 

of  Oysters. 


FAUNA  (Lat.  Fauni,  the  rural  deities  of  the  Romans).  The 
general  assemblage  of  the  animals  of  any  region  or  district. 

FAVOSITES  (Lat.  favos,  a  honeycomb).  A  genus  of  Tabulate 
Corals. 

FENESTELLID^:  (Lat.  fenestella,  a  little  window).  The  "Lace- 
corals,  "  a  group  of  Palaeozoic  Polyzoans. 

FILICES  (Lat.  filix,  a  fern).  The  order  of  Cryptogamic  plants 
comprising  the  Ferns. 

FILIFORM   (Lat.  filum,  a  thread;  forma,  shape).     Thread-shaped. 

FLORA  (Lat.  Flora,  the  goddess  of  flowers).  The  general 
assemblage  of  the  plants  of  any  region  or  district. 

FORAMINIFERA  (Lat.  foramen,  an  aperture;  fero,  I  carry).  An 
order  of  Protozoa,  usually  characterized  by  the  possession  of 
a  shell  perforated  by  numerous  pseudopodial  apertures. 

FRUGIVOROUS  (Lat.  frux,  fruit;  voro,  I  devour).  Living  upon 
fruits. 

FUCOIDS  (Lat.  fucus,  sea-weed;  Gr.  eidos,  likeness).  Fossils 
often  of  an  obscure  nature,  believed  to  be  the  remains  of 
sea-weeds. 

FUSULINA  (Lat.  fusus,  a  spindle).  An  extinct  genus  of  Fora- 
minifera. 


GLOSSARY.  403 


GANOID  (Gr.  ganos,  splendour,  brightness).  Applied  to  those 
scales  or  plates  which  are  composed  of  an  inferior  layer  of 
true  bone  covered  by  a  superior  layer  of  polished  enamel. 

GANOIDEI.     An  order  of  Fishes. 

GASTEROPODA  (Gr.  gaster,  stomach;  pous,  foot).  The  class  of 
the  Mollusca  comprising  the  ordinary  Univalves,  in  which 
locomotion  is  usually  effected  by  a  muscular  expansion  of 
the  under  surface  of  the  body  (the  "foot"). 

GLOBIGERINA  (Lat.  globus,  a  globe;  gero,  I  carry).  A  genus  of 
Foraminifera. 

GLYPTODON  (Gr.  glupho,  I  engrave;  odous,  tooth).  An  extinct 
genus  of  Armadillos,  so-named  in  allusion  to  the  fluted  teeth. 

GONIATITES  (Gr.  gonia,  angle).  A  genus  of  Tetrabanchiate 
Cephalopods. 

GRALLATORES  (Lat.  gralla,  stilts).  The  order  of  the  long-legged 
Wading  Birds. 

GRAPTOLITID^:  (Gr.  grapho.,  I  write;  lithos,  stone).  An  extinct 
sub-class  of  the  Hydrosoa. 

GYMNOSPERMS  (Gr.  gumncs,  naked;  sperma,  seed).  The  Conifers 
and  Cycads,  in  which  the  seed  is  not  protected  within  a  seed- 
vessel. 

H 

HALITHERIUM  (Gr.  hals,  sea;  thtrion,  beast).     An  extinct  genus 

of  Sea-cows    (Sirenia}. 

HAMITES   (Lat.  hamus,  a  hook).     A  genus  of  the  Ammonitidce. 
HELIOPHYLLUM    (Gr.   helios,  the  sun;  phullon,  leaf).     A  genus 

of  Rugose   Corals. 
HELLADOTHERIUM     (Gr.    HZllas,    Greece;    thVrion,    beast).      An 

extinct  genus  of  Ungulate  Mammals. 
HEMIPTERA  (Gr.  hemi;  and  pteron,  wing).     An  order  of  Insects 

in  which  the  anterior  wings  are  sometimes  "  hemelytra.  " 
HESPERORNIS  (Gr.  Hesperos,  the  evening  star;  ornis,  bird).     An 

extinct  genus   of   Birds. 
HETEROCERCAL    (Gr.  heteros,  diverse;   kerkos,  tail).     Applied  to 

the  tail  of  Fishes  when  it  is  unsymmetrical,  or  composed  of 

two  unequal  lobes. 
HETF.ROPODA    (Gr.   heteros,   diverse;   podes,   feet).     An   aberrant 

group  of  the  Gasteropods,  in  which  the  foot  is  modified  so  as 

to  form  a  swimming  organ. 
HIPPARION   (Gr.  hipparion,  a  little  horse).     An  extinct  genus  of 

E  quid  a. 
HIPPOPOTAMUS  (Gr.  hippos,  horse;  potamos,  river).    A  genus  of 

hoofed  Quadrupeds — the  "  River-horses.  " 
HIPPURITID^:  (Gr.  hippos,  horse;  oura,  tail).     An  extinct  family 

of  Bivalve  Molluscs. 
HOLOPTYCHIUS  (Gr.  holos,  whole;  ptuche*,  wrinkle).     An  extinct 

genus  of  Ganoid  Fishes. 
HOLOSTOMATA  (Gr.  holos,  whole;  stoma,  mouth).     A  division  of 

Gasteropodous  Molluscs,  in  which  the   aperture  of  the  shell 

is  rounded,  or  "  entire.  " 


404  GLOSSARY. 

HOLOTHUROIDEA  (Gr.  holothourion,  a  kind  of  zoophyte ;  and  eidos, 

form).     An  order  of  Echinodermata  comprising  the  Trepangs. 
HOMOCERCAL   (Gr.  homos,  same;   kerkos,  tail).     Applied  to  the 

tail  of  Fishes  when  it   is   symmetrical,   or  composed  of   two 

equal  lobes. 
HYBODONTS    (Gr.    hubos,   curved;    odous,   tooth).     A   group    of 

Fishes  of  which  Hybodus  is  the  type-genus. 
HYDROIDA    (Gr.    hudra,   water-serpent;    and   eidos,   form).     The 

sub-class  of  the  Hydrozoa,  which  comprises  the  animals  most 

nearly  allied  to  the  Hydra. 
HYDROZOA    (Gr.   hudra;   and  zoVn,  animal).     The   class   of   the 

Ccclenterata    which    cqmprises    animals    constructed    after    the 

type  of  the  Hydra. 
HYMENOPTERA   (Gr.  humen,  a  membrane;  pteron,  a  wing).     An 

order  of   Insects    (comprising  Bees,   Ants,   etc.)    characterized 

by  the  possession  of  four  membranous  wings. 


ICHTHYODORULITE  (Gr.  ichthus,  fish;  dorus,  spear;  lithos,  stone). 
The  fossil  fin-spine  of  Fishes. 

ICHTHYOPTERYGIA  (Gr.  ichthus \  pterux,  wing).  An  extinct  order 
of  Reptiles. 

ICHTHYORNIS  (Gr.  ichthus,  fish;  ornis,  bird).  An  extinct  genus 
of  Birds. 

ICHTHYOSAURIA  (Gr.  ichthus ;  saura,  lizard).  Synonymous  with 
Ichthyopterygia. 

IGUANODON  {Iguana,  a  living  lizard;  Gr.  odous,  tooth).  A  genus 
of  Deinosaurian  Reptiles. 

INCISOR  (Lat.  incido,  I  cut).  The  cutting  teeth  fixed  in  the  inter- 
maxillary bones  of  the  Mammalia,  and  the  corresponding  teeth 
in  the  lower  jaw. 

INEQUILATERAL.  Having  the  two  sides  unequal,  as  in  the  case 
of  the  shells  of  the  ordinary  bivalves  (Lamellibranchiata). 
When  applied  to  the  shells  of  the  Foraminifera,  it  implies  that 
the  convolutions  of  the  shell  do  not  lie  in  the  same  plane, 
but  are  obliquely  wound  round  an  axis. 

INEQUIVALVE.     Composed  of  two  unequal  pieces  or  valves. 

INOCERAMUS  (Gr.  is,  a  fibre;  keramos,  an  earthen  vessel).  An 
extinct  genus  of  Bivalve  Molluscs. 

INSECTA  (Lat.  inseco,  I  cut  into).  The  class  of  articulate 
animals  commonly  known  as  Insects. 

INSECTIVORA  (Lat.  insectum,  an  insect;  voro,  I  devour).  An 
order  of  Mammals. 

INSECTIVOROUS.     Living  upon  Insects. 

INSESSORES  (Lat.  insedeo,  I  sit  upon).  The  order  of  the  Perch- 
ing Birds,  often  called  Passeres. 

INTERAMBULACRA.  The  rows  of  plates  in  an  Echinoid  which  are 
not  perforated  for  the  emission  of  the  "  tube-feet.  " 

INTERMAXILL^E  or  PR^:MAXILL/E.  The  two  bones  which  are 
situated  between  the  two  superior  maxillae  in  Vertebrata.  In 
man,  and  some  monkeys,  the  praemaxillae  anchylose  with  the 
maxillae,  so  as  to  be  irrecognizable  in  the  adult. 


GLOSSARY.  405 

INVERTEBRATA  (Lat.  in,  without;  vertebra,  a  bone  of  the  back). 
Animals  without  a  spinal  column  or  backbone. 

ISOPODA  (Gr.  isos,  equal;  podes,  feet).  An  order  of  Crusta- 
cea in  which  the  feet  are  like  one  another  and  equal. 


K 

KAINOZOIC  (Gr.  kainos,  recent;  zoe,  life).  The  Tertiary  period 
in  Geology  comprising  those  formations  in  which  the  organic 
remains  approximate  more  or  less  closely  to  the  existing  fauna 
and  flora. 


LABYRINTHODONTIA  (Gr.  laburinthos,  a  labyrinth;  odous,  tooth). 
An  extinct  order  of  Amphibia,  so-called  from  the  complex 
microscopic  structure  of  the  teeth. 

LACERTILIA  (Lat.  lacerta,  a  lizard).  An  order  of  Reptilia  com- 
prising the  Lizards  and  Slow-worms. 

LAMELLIBRANCHIATA  (Lat.  lamella,  a  plate;  Gr.  bragchia,  gill). 
The  class  of  Mollusca  comprising  the  ordinary  bivalves,  char- 
acterized by  the  possession  of  lamellar  gills. 

LEPIDODENDRON  (Gr.  lepis,  a  scale;  dendron,  a  tree).  A  genus  of 
extinct  plants,  so-named  from  the  scale-like  scars  upon  the 
stem  left  by  the  falling  off  of  the  leaves. 

LEPIDOPTERA  (Gr.  lepis,  a  scale;  pteron,  a  wing).  An  order  of 
Insects,  comprising  Butterflies  and  Moths,  characterized  by 
possessing  four  wings  which  are  usually  covered  with  minute 
scales. 

LEPIDOSIREN  (Gr.  lepis,  a  scale;  seiren,  a  siren — the  generic  name 
of  the  Mud-eel  or  Siren  lacertina).  A  genus  of  Dipnoous 
fishes,  comprising  the  "  Mud-fishes.  " 

LEPIDOSTROBUS  (Gr.  lepis.  a  scale;  strobilos,  a  fir-cone).  A  genus 
founded  on  the  cones  of  Lepidodendron. 

LEPT^NA  (Gr.  leptos,  slender).  A  genus  of  Brachiopods. 

LINGULA  (Lat.  lingula,  a  little  tongue).  A  genus  of  Brachio- 
pods. 

LYCOPODIACE^:  (Gr.  lupos,  a  wolf;  pous,  foot).  The  group  of 
Cryptogamic  plants  generally  known  as  "  Club-mosses. " 

M 

MACH^RACANTHUS  (Gr.  machaira,  a  sabre ;  acantha,  thorn  or 
spine).  An  extinct  genus  of  Fishes. 

MACHAIRODUS  (Gr.  machaira,  a  sabre;  odous,  tooth).  An  ex- 
tinct genus  of  Carnivora. 

MACROTHERIUM  (Gr.  makros,  long;  therion,  beast).  An  extinct 
genus  of  Edentata. 

MACRURA  (Gr.  makros,  long;  oura,  tail).  A  tribe  of  Decapod 
Crustaceans  with  long  tails  (e.  g.,  the  Lobster,  Shrimp,  etc.) 

MAMMALIA  (Lat.  mamma,  the  breast).  The  class  of  Verte- 
brate animals  which  suckle  their  young. 


4o6  GLOSSARY. 

MANDIBLE  (Lat.  mandibulum,  a  jaw).  The  upper  pair  of  jaws 
in  Insects;  also  applied  to  one  of  the  pairs  of  jaws  in  Crus- 
tacea and  Spiders,  to  the  beak  of  Cephalopods,  the  lower  jaw 
of  Vertebrates,  etc. 

MANTLE.  The  external  integument  of  most  of  the  Mollusca, 
which  is  largely  developed,  and  forms  a  cloak  in  which  the 
viscera  are  protected.  Technically  called  the  "  pallium. " 

MANUS  (Lat.  the  hand).     The  hand  of  the  higher  Vertebrates. 

MARSIPOBRANCHII  (Gr.  marsipos,  a  pouch;  bragchia,  gill).  The 
order  of  Fishes  comprising  the  Hag-fishes  and  Lampreys,  with 
pouch-like  gills. 

MARSUPIALIA  (Lat.  marsupium,  a  pouch).  An  order  of  Mam- 
mals in  which  the  females  mostly  have  an  abdominal  pouch 
in  which  the  young  are  carried. 

MASTODON  (Gr.  mastos,  nipple;  odous,  tooth).  An  extinct  genus 
of  Elephantine  Mammals. 

MEGALONYX  (Gr.  megas,  great;  onux,  nail).  An  extinct  genus 
of  Edentate  Mammals. 

MEGALOSAURUS  (Gr.  megas,  great;  saura,  lizard).  A  genus  of 
Deinosaurian  Reptiles. 

MEGATHERIUM  (Gr.  megas,  great;  thZrion,  beast).  An  extinct 
genus  of  Edentata. 

MESOZOIC  (Gr.  mesos,  middle;  and  zoe,  life).  The  Secondary 
period  in  Geology. 

MICROLESTES  (Gr.  mikros,  little;  lestes,  thief).  An  extinct  genus 
of  Triassic  Mammals. 

MILLEPORA  (Lat.  mille,  one  thousand;  porus,  a  pore).  A  genus 
of '"Tabulate  Corals." 

MIOCENE  (Gr.  melon,  less;  kainos,  new).  The  Middle  Tertiary 
period. 

MOLARS  (Lat.  mola,  a  mill).  The  "grinders"  in  man,  or  the 
teeth  in  diphyodont  Mammals  which  are  not  preceded  by 
milk-teeth. 

MOLLUSCA  (Lat.  mollis,  soft).  The  sub-kingdom  which  includes 
the  Shell-fish  proper,  the  Polysoa,  the  Tunicata,  and  the  Lamp- 
shells  ;  so-called  from  the  generally  soft  nature  of  their 
bodies. 

MOLLUSCOIDA  (Mollusca;  Gr.  eidos,  form).  The  lower  division 
of  the  Mollusca,  comprising  the  Polysoa,  Tunicata,  and  Brach- 
iopoda. . 

MONOGRAPTUS  (Gr.  monos,  single;  grapho,  I  write).  A  genus 
of  Graptolites. 

MYLODON  (Gr.  mulos,  a  mill;  odous,  tooth).  An  extinct  genus 
of  Edentate  Mammals. 

MYRIAPODA  or  MYRIOPODA  (Gr.  murios,  ten  thousand;  podes, 
feet).  A  class  of  Arthropoda  comprising  the  Centipedes  and 
their  allies,  characterized  by  their  numerous  feet. 

N 

NATATORES  (Lat.  nare,  to  swim).  The  order  of  the  Swim- 
ming Birds. 

NATATORY   (Lat.  nare,  to  swim).     Formed  for  swimming. 
NAUTILOID.     Resembling  the  shell  of  the  Nautilus  in  shape. 


GLOSSARY.  40? 

NERVURES   (Lat.  nervus,  a  sinew).     The  ribs  which  support  the 

membranous   wings  of  insects. 
NEUROPTERA   (Gr.  neuron,  a  nerve;  pier  on,  a  wing).     An  order 

of    Insects    characterized    by    four    membranous  .  wings    with 

numerous  reticulated  nervures    (e.  g.,  Dragon-flies). 
NEUROPTERIS   (Gr.  neuron,  a  nerve;  pteris,  a  fern).     An  extinct 

genus  of  Ferns. 
NOTHOSAURUS    (Gr.    nothos,   spurious;   saura,  lizard).     A  genus 

of  Plesiosaurian  Reptiles. 
NOTOCHORD    (Gr.   notos,  back;   chorde,   string).     A  cellular  rod 

which  is  developed  in  the  embryo  of  Vertebrates  immediately 

beneath  the  spinal  cord,  and  which  is  usually  replaced  in  the 

adult  by  the  vertebral  column.     Often  it  is  spoken  of  as  the 

"  chorda   dorsalis.  " 
NUDIBRANCHIATA    (Lat.   nudus,  naked;   and  Gr.   bragchia,  gill). 

An  order  of  the  Gasteropoda  in  which  the  gills  are  naked. 
NUMMULINA    (Lat.   nummus,  a  coin).     A  genus  of  Foramini- 

fera,  comprising  the  coin-shaped  "  Nummulites. " 


O 

OBOLELLA  (Lat.  dim  of  obolus,  a  small  coin).     An  extinct  genus 

of  Brachiopods. 

OCCIPITAL.  Connected  with  the  occiput,  or  the  back  part  of  the 
head. 

OCEANIC.  Applied  to  animals  which  inhabit  the  open  ocean 
(=pelagic). 

ODONTOPTERYX  (Gr.  odous,  tooth;  pterux,  wing).  An  extinct 
genus  of  Birds. 

ODONTORNITHES  (Gr.  odous,  tooth;  ornis,  bird).  The  extinct 
order  of  Birds,  comprising  forms  with  distinct  teeth  in  sockets. 

OLIGOCENE  (Gr.  oligos,  few;  kainos,  new).  A  name  used  by 
many  Continental  geologists  as  synonymous  with  the  Lower 
Miocene. 

OPHIDIA  (Gr.  ophis,  a  serpent).  The  order  of  Reptiles  com- 
prising the  Snakes. 

OPHIUROIDEA  (Gr.  ophis,  snake;  oura,  tail;  eldos,  form).  An 
order  of  Echinodermata,  comprising  the  Brittle-stars  and  Sand- 
stars. 

ORNITHOSCELIDA  (Gr.  ornis,  bird;  skelo,  leg).  Applied  by 
Huxley  to  the  Deinosaurian  Reptiles,  together  with  the  genus 
Compsognathus,  on  account  of  the  bird-like  character  of  their 
hind-limbs. 

ORTHIS  (Gr.  orthos,  straight).  A  genus  of  Brachiopods,  named 
in  allusion  to  the  straight  hinge-line. 

ORTHOCERATID^:  (Gr.  orthos,  straight;  keras,  horn).  A  family  of 
the  Nautilidcz,  in  which  the  shell  is  straight,  or  nearly  so. 

ORTHOPTERA  (Gr.  orthos,  straight;  pteron,  wing).  An  order  of 
Insects. 

OSTEOLEPIS  (Gr.  osteon,  bone;  lepis,  scale).  An  extinct  genus 
of  Ganoid  Fishes. 

OSTRACODA  (Gr.  ostrakon,  a  shell).  An  order  of  small  Crus- 
taceans which  are  enclosed  in  bivalve  shells. 


4o8  GLOSSARY. 

OTODUS    (Gr.    ota,   ears;    odous,   tooth).     An   extinct  genus   of 

Sharks. 
OUDENODON  (Gr.  ouden,  none;  odous,  tooth).    A  genus  of  Dicy- 

nodont  Reptiles. 
OVIBOS   (Lat.  ovis,  sheep;  bos,  ox).     The  genus  comprising  the 

Musk-ox. 


PACHYDERM  ATA  (Gr.  pachus,  thick;  derma,  skin).  An  old  Mam- 
malian order  constituted  by  Cuvier  for  the  reception  of  the 
Rhinoceros,  Hippopotamus,  Elephant,  etc. 

PALE  ASTER  (Gr.  palaios,  ancient;  aster,  star).  An  extinct 
genus  of  Star-fishes. 

PALEOCARIS  (Gr.  palaios,  ancient;  karis,  shrimp).  An  extinct 
genus  of  Decapod  Crustaceans. 

PALEOLITHIC  (Gr.  palaios,  ancient;  lithos,  stone).  Applied  to 
the  rude  stone  implements  of  the  earliest  known  races  of 
men,  to  the  men  who  made  these  implements,  or  to  the  period 
at  which  they  were  made. 

PALEONTOLOGY  (Gr.  palaios,  ancient;  and  logos,  discourse).  The 
science  of  fossil  remains  or  of  extinct  organized  beings. 

PAL/EOPHIS  (Gr.  palaios,  ancient;  ophis,  serpent).  An  extinct 
genus  of  Snakes. 

PALEOSAURUS  (Gr.  palaios,  ancient;  saura,  lizard).  A  genus 
of  Thecodont  Reptiles. 

PALEOTHERIDE  (Gr.  palaios,  ancient;  therion,  beast).  A  group  of 
Tertiary  Ungulates. 

PALEOZOIC  (Gr.  palaios,  ancient;  and  zoe,  life).  Applied  to 
the  oldest  of  the  great  geological  epochs. 

PARADOXIDES  (Lat.  paradoxus,  marvellous).  A  genus  of  Trilo- 
bites. 

PATAGIUM  (Lat.  the  border  of  a  dress).  Applied  to  the  ex- 
pansion of  the  integument  by  which  Bats,  Flying  Squirrels, 
and  other  animals  support  themselves  in,  the  air. 

PECOPTERIS  (Gr.  peko,  I  comb;  pteris,  a  fern).  An  extinct  genus 
of  Ferns. 

PECTEN  (Lat.  a  comb).  The  genus  of  Bivalve  Molluscs  com- 
prising the  Scallops. 

PECTORAL  (Lat.  pectus,  chest).  Connected  with,  or  placed  upon, 
the  chest. 

PENTACRINUS  (Gr.  penta,  five;  krinon,  lily).  A  genus  of  Crinoids 
in  which  the  column  is  five-sided. 

PENTAMERUS  (Gr.  penta,  five;  meros,  part).  An  extinct  genus 
of  Brachiopods. 

PENTREMITES  (Gr.  penta,  five;  trenia,  aperture).  A  genus  of 
Blastoidea,  so-named  in  allusion  to  the  apertures  at  the  sum- 
mit of  the  calyx. 

PERENNIBRANCHIATA  (Lat.  perennis,  perpetual ;  Gr.  brag chia,  gill). 
Applied  to  those  Amphibia  in  which  the  gills  are  permanently 
retained  throughout  life. 

PERISSODACTYLA  (Gr.  perissos,  uneven;  daktulos,  finger).  Ap- 
plied to  those  Hoofed  Quadrupeds  (Ungulata)  in  which  the 
feet  have  an  uneven  number  of  toes. 


GLOSSARY.  409 

PETALOID.     Shaped  like  the  petal  of  a  flower. 

PHACOPS  (Gr.  phakf,  a  lentil;  ops,  the  eye).    A  genus  of  Trilo- 

bites. 
PHALANGES  (Gr.  phalanx,  a  row).     The  small  bones  composing 

the    digits    of    the    higher    Vertebrata.     Normally,    each   digit 

has  three  phalanges. 
PHANEROGAMS  (Gr.  phaneros,  visible;  gamos,  marriage).    Plants 

which  have  the  organs  of  reproduction  conspicuous,  and  which 

bear  true  flowers. 
PHARYNGOBRANCHII  (Gr.  pharugx,  pharynx;  bragchia,  gill).    The 

order  of  Fishes  comprising  only  the  Lancelet. 
PHASCOLOTHERIUM    (Gr.  phaskolos,  a  pouch;   therion,  a  beast). 

A  genus  of  Oolitic  Mammals. 
PHRAGMACONE   (Gr.  phragma,  a  partition;  and  konos,  a  cone). 

The  chambered  portion  of  the  internal  shell  of  a  Belemnite. 
PHYLLOPODA  (Gr.  phullon,  leaf;  and  pous,  foot).     An  order  of 

Crustacea. 

PINNATE   (Lat.  pinna,  a  feather).     Feather-shaped;  or  possess- 
ing lateral  processes. 
PINNIGRADA  (Lat.  pinna,  a  feather;  gradior,  I  walk).    The  group 

of    Carnivora,   comprising   the    Seals    and    Walruses,    adapted 

for  an  aquatic  life.     Often  called  Pinfiipedia. 
PINNULE    (Lat.  dim.  of  pinna).     The  lateral  processes  of  the 

arms  of  Crinoids. 
PISCES  (Lat.  piscis,  a  fish).    The  class  of  Vertebrates  comprising 

the  Fishes. 
PLACOID    (Gr.    plax,    a    plate;    eidos,    form).      Applied    to    the 

irregular  bony  plates,  grains  or  spines  which  are  found  in  the 

skin  of  various  fishes  (Elasmobranchii). 
PLAGIOSTOMI     (Gr.    plagios,    transverse;    stoma,    mouth).     The 

Sharks  and  Rays,  in  which  the  mouth  is  transverse,  and  is 

placed  on  the  under  surface  of  the  head. 

PLATYCERAS  (Gr.  plains,  broad;  keras,  horn).     A  genus  of  Uni- 
valve Molluscs. 
PLATYCRINUS    (Gr.    plains,   broad;    krinon,   lily).     A   genus    of 

Crinoidea. 
PLATYRHINA   (Gr.  plains,  broad;  rhines,  nostrils).     A  group  of 

the  Quadrumana. 
PLATYSOMUS  (Gr.  plains,  wide;  soma,  body).   A  genus  of  Ganoid 

Fishes. 
PLEISTOCENE   (Gr.  pleistos,  most;  kainos,  new).     Often  used  as 

synonymous  with  "  Post-Pliocene.  " 
PLEUROTOMARIA   (Gr.  pleura,  the  side;   tome",  notch).     A  genus 

of  Univalve  shells. 
PLIOCENE   (Gr.  pleion,  more;  kainos,  new).     The  later  Tertiary 

period. 
PLIOPITHECUS    (Gr.    pleion,   more;    pithekos,   ape).     An   extinct 

genus  of   Monkeys. 
PLIOSAURUS    (Gr.   pleion,  more;    saura,   lizard).      A    genus    of 

Plesiosaurian  Reptiles. 
POLYCYSTINA   (Gr.  polus,  many;  and  kustis,  a  cyst).     An  order 

of  Protozoa  with  foraminated  siliceous  shells. 
POLYPARY.     The  hard  chitinous  covering  secreted  by  many  of 

the  Hydrozoa. 


410  GLOSSARY. 

POLYPE  (Gr.  polus,  many;  pous,  foot).  Restricted  to  the  single 
individual  of  a  simple  Actinozoon,  such  as  Sea-anemone,  or 
to  the  separate  zooids  of  a  compound  Actinozotin.  Often  ap- 
plied indiscriminately  to  any  of  the  Ccelenterata,  or  even  to 
the  Polyzoa.  N 

POLYPORA  (Gr.  polus,  many;  poros,  a  passage).  A  genus  of 
Lace-corals  (Fenestellida.} 

POLYTHALAMOUS  (Gr.  polus \  and  thalamos,  chamber).  Having 
many  chambers;  applied  to  the  shells  of  Foraminifera  and 
Cephalopoda. 

POLYZOA  (Gr.  polus;  and  zo'6n,  animal).  A  division  of  the 
Molluscoida  comprising  compound  animals,  such  as  the  Sea- 
mat — sometimes  called  Bryozoa. 

PORIFERA  (Lat.  porus,  a  pore;  and  fero,  I  carry).  Sometimes 
used  to  designate  the  Foraminifera,  or  the  Sponges. 

PR^EMOLARS  (Lat.  pros,  before;  molar es,  the  grinders).  The 
molar  teeth  of  Mammals  which  succeed  the  molars  of  the 
milk-set  of  teeth.  In  man,  the  bicuspid  teeth. 

PROBOSCIDEA  (Lat.  proboscis,  the  snout).  The  order  of  Mam- 
mals comprising  the  Elephants. 

PROCCELOUS  (Gr.  pro,  before;  koilos,  hollow).  Applied  to  ver- 
tebrae the  bodies  of  which  are  hollow  or  concave  in  front. 

PRODUCTA  (Lat.  productus,  drawn  out  or  extended).  An  extinct 
genus  of  Brachiopods,  in  which  the  shell  is  "  eared, "  or  has 
its  lateral  angles  drawn  out. 

PROTICHNITES  (Gr.  protos,  first;  ichnos,  footprint).  Applied  to 
certain  impressions  in  the  Potsdam  sandstone  of  North  Amer- 
ica, believed  to  have  been  produced  by  large  Crustaceans. 

PROTOPHYTA  (Gr.  protos;  and  phut  on,  plant).  The  lowest 
division  of  plants. 

PROTOPLASM  (Gr.  protos;  and  plasso,  I  mould).  The  elementary 
basis  of  organized  tissues.  Sometimes  used  synonymously  for 
the  "  sarcode  "  of  the  Protozoa. 

PROTOROSAURUS  or  PROTEROSAURUS  (Gr.  protos,  first;  orao,  I  se« 
or  discover;  saura,  lizard;  or  proteros,  earlier;  saura,  lizard). 
A  genus  of  Permian  lizards. 

PROTOZOA  (Gr.  protos;  and  zoon,  animal).  The  lowest  division 
of  the  animal  kingdom. 

PSAMMODUS  (Gr.  psammos,  sand;  odous,  tooth).  An  extinct 
genus  of  Cestraciont  Sharks. 

PSEUDOPODIA  (Gr.  pseudos,  falsity;  and  pous,  foot).  The  exten- 
sions of  the  body-substance  which  are  put  forth  by  the  Rhizo- 
poda  at  will,  and  which  serve  for  locomotion  and  prehension. 

PSILOPHYTON  (Gr.  psilos,  bare;  phuton,  plant).  An  extinct  genus 
of  Lycopodiaceous  plants. 

PTERANODON  (Gr.  pteron,  wing;  a,  without;  odous,  tooth).  A 
genus  of  Pterosaurian  ^Reptiles. 

PTERASPIS  (Gr.  pteron,  wing;  aspis,  shield).  A  genus  of  Ganoid 
Fishes. 

PTERICHTHYS  (Gr.  pteron,  wing;  ichthus,  fish).  A  genus  of 
Ganoid  Fishes. 

PTERODACTYLUS  (Gr.  pteron,  wing;  daktulos,  finger).  A  genus 
of  Pterosaurian  Reptiles. 


GLOSSARY.  411 

PTEROPODA   (Gr.  pteron,  wing;  and  pous,  foot).     A  class  of  the 

Mollusca   which    swim    by    means    of    fins    attached    near    the 

head. 
PTEROSAURIA  (Gr.  pteron,  wing;  saura,  lizard).    An  extinct  order 

of  Reptiles. 
PTILODICTYA  (Gr.  ptilon,  a  feather;  diktuon,  a  net).     An  extinct 

genus  of  Polyzoa. 
PTYCHOCERAS   (Gr.  ptuche*,  a  fold;  keras,  a  horn).     A  genus  of 

Ammonitidcz 

PULMONATE.     Possessing  lungs. 
PYRIFORM  (Lat.  pyrus,  a  pear;  and  forma,  form).     Pear-shaped. 

Q 

QUADRUMANA  (Lat.  quatuor,  four;  manus,  hand).  The  older 
of  Mammals  comprising  the  Apes,  Monkeys,  Baboons,  Lemurs, 
etc. 

R 

RADIATA  (Lat.  radius,  a  ray).  Formerly  applied  to  a  large 
number  of  animals  which  are  now  placed  in  separate  sub- 
kingdoms  (e.  g.,  the  Coclenterata,  the  Ecliinodermata,  the/n- 
fusoria,  etc.) 

RADIOLARIA   (Lat.  radius,  a  ray).     A  division  of  Protozoa. 

RAMUS  (Lat.  a  branch).  Applied  to  each  half  or  branch  of  the 
lower  jaw,  or  mandible,  of  Vertebrates. 

RAPTORES  (Lat.  rapto,  I  plunder).  The  order  of  the  Birds  of 
Prey. 

RASORES  (Lat.  rado,  I  scratch).  The  order  of  the  Scratching 
Birds  (Fowls,  Pigeons,  &c.) 

RECEPTACULITES  (Lat.  receptaculmn,  a  storehouse).  An  extinct 
genus  of  Protozoa. 

REPTILIA  (Lat.  repto,  I  crawl).  The  class  of  the  Vertebrata 
comprising  the  Tortoises,  Snakes,  Lizards,  Crocodiles,  etc. 

RETEPORA  (Lat.  rete,  a  net;  porus,  a  pore).  A  genus  of  Lace- 
corals  (Polysoa). 

RHAMPHORHYNCHUS  (Gr,  rhamphos,  beak;  rhugchos,  nose).  A 
genus  of  Pterosaurian  Reptiles. 

RHINOCEROS  (Gr.  rhis,  the  nose;  keras,  horn).  A  genus  of 
Hoofed  Quadrupeds. 

RHIZOPODA  (Gr.  rhiza,  a  root;  and  pous,  foot).  The  division  of 
Protozoa  comprising  all  those  which  are  capable  of  emitting 
pseudopodia. 

RHYNCHOLITES  (Gr.  rhugchos,  beak;  and  lithos,  stone).  Beak- 
shaped  fossils  consisting  of  the  mandibles  of  Cephalopoda. 

RHYNCHONELLA  (Gr.  rhugchos,  nose  or  beak).  A  genus  of 
Brachiopods. 

RODENTIA  (Lat.  rodo,  I  gnaw).  An  order  of  the  Mammals; 
often  called  Glires  (Lat.  glis,  a  dormouse). 

ROTALIA  (Lat.  rota,  a  wheel).     A  genus  of  Foraminifera. 

RUGOSA  (Lat.  rugosus,  wrinkled).     An  order  of  Corals. 

RUMINANTIA  (Lat.  ruminor,  I  chew  the  cud).  The  group  of 
Hoofed  Quadrupeds  (Ungulata)  which  "ruminate"  or  chew 
the  cud. 


412  GLOSSARY. 

S 


SARCODE  (Gr.  sarx,  flesh;  eidos,  form).  The  jelly-like  substance 
of  which  the  bodies  of  the  Protozoa  are  composed.  It  is  an 
albuminous  body  containing  oil-granules,  and  is  sometimes 
called  "  animal  protoplasm.  " 

SAURIA  (Gr.  saura,  a  lizard).  Any  lizard-like  Reptile  is  often 
spoken  of  as  a  "  Saurian ; "  but  the  term  is  sometimes  re- 
stricted to  the  Crocodiles  alone,  or  to  the  Crocodiles  and 
Larcertilians. 

SAUROPTERYGIA  (Gr.  saura;  pterux,  wing).  An  extinct  order 
of  Reptiles,  called  by  Huxley  Plesiosauria,  from  the  typical 
genus  Plesiosaurus. 

SAURUR^E  (Gr.  saura;  oura,  tail).  The  extinct  order  of  Birds 
comprising  only  the  Archocopteryx. 

SCANSORES  (Lat.  scando,  I  climb).  The  order  of  the  Climbing 
Birds  (Parrots,  Woodpeckers,  &c.) 

SCAPHI    (Lat.  scapha,   a  boat).     A  genus   of  the  Ammonitida. 

SCOLITHUS  (Gr.  skolex,  a  worm;  lithos,  a  stone).  The  vertical 
burrows  of  sea-worms  in  rocks. 

SCUTA  (Lat.  scutum,  a  shield).  Applied  to  any  shield-like  plates ; 
especially  to  those  which  are  developed  in  the  integument  of 
many  Reptiles. 

SELACHIA  or  SELACHII  (Gr.  selachos,  a  cartilaginous  fish,  probably 
a  shark).  The  sub-order  of  Elasmobranchii  comprising  the 
Sharks  and  Dog-fishes. 

SEPIOSTAIRE.  The  internal  shell  of  the  Sepia,  commonly  known 
as  the  "  cuttle-bone.  " 

SEPTA.     Partitions. 

SERPENTIFORM.    Resembling  a  serpent  in  shape. 

SERTULARIDA   (Lat.  sertutn,  a  wreath).     An  order  of  Hydrozoa. 

SESSILE  (Lat.  sedo,  I  sit).  Not  supported  upon  a  stalk  or  ped- 
uncle; attached  by  a  base. 

SET^:  (Lat.  bristles).     Bristles  orjong  stiff  hairs. 

SIGILLARIOIDS  (Lat.  sigilla,  little  images).  A  group  of  extinct 
plants  of  which  Sigillaria  is  the  type,  so-called  from  the  seal- 
like  markings  on  the  bark. 

SILICEOUS   (Lat.  silex,  flint).     Composed  of  flint. 

SINISTRAL  (Lat.  sinistra,  the  left  hand).  Left-handed;  applied 
to  the  direction  of  the  spiral  in  certain  shells,  which  are  said 
to  be  "  reversed.  " 

SIPHON  (Gr.  a  tube).  Applied  to  the  respiratory  tubes  in  the 
Mollusca;  also  to  other  tubes  of  different  functions. 

SIPHONIA  (Gr.  siphon,  a  tube).     A  genus  of  fossil  Sponges. 

SIPHONOSTOMATA  (Gr.  siphon;  and  stoma,  mouth).  The  division 
of  Gasteropodous  Molluscs  in  which  the  aperture  of  the  shell 
is  not  "  entire, "  but  possesses  a  notch  or  tube  for  the  emission 
of  the  respiratory  siphon. 

SIPHUNCLE  (Lat.  siphunculus,  a  little  tube).  The  tube  which 
connects  together  the  various  chambers  of  the  shell  of  certain 
Cephalopoda  (e.  g.,  the  Pearly  Nautilus). 

SIRENIA  (Gr.  seiren,  a  mermaid).  The  order  of  Mammalia  com- 
prising the  Dugongs  and  Manatees. 


GLOSSARY.  413 

SIVATHERIUM  (Siva,  a  Hindoo  deity;  Gr.  therion,  beast).  An 
extinct  genus  of  Hoofed  Quadrupeds. 

SOLIDUNGULA  (Lat.  solidus,  solid;  ungula,  a  hoof).  The  group 
of  Hoofed  Quadrupeds  comprising  theHorse,  Ass,  and  Zebra, 
in  which  each  foot  has  only  a  single  solid  hoof.  Often  called 
Solipedia. 

SPHENOPTERIS  (Gr.  sphe*n,  a  wedge;  pteris,  a  fern).  An  extinct 
genus  of  ferns. 

SPICULA  (Lat.  spiculum,  a  point).     Pointed  needle-shaped  bodies. 

SPIRIFERA  (Lat.  spira,  a  spire  or  coil;  fero,  I  carry).  An  ex- 
tinct genus  of  Brachiopods,  with  large  spiral  supports  for  the 
"  arms. " 

SPIRORBIS  (Lat.  spira,  a  spire;  prbis,  a  circle).  A  genus  of  tube- 
inhabiting  Annelides,  in  which  the  shelly  tube  is  coiled  into 
a  spiral  disc. 

SPONGIDA  (Gr.  spoggos,  a  sponge).  The  division  of  Protozoa, 
commonly  known  as  sponges. 

STALACTITES  (Gr.  stalasso,  I  drop).  Icicle-like  encrustations  and 
deposits  of  lime,  which  hang  from  the  roof  of  caverns  in 
limestone. 

STALAGMITE  (Gr.  stalagma,  a  drop).  Encrustations  of  lime 
formed  on  the  floor  of  caverns  which  are  hollowed  out  of 
limestone. 

STIGMARIA  (Gr.  stigma,  a  mark  made  with  a  pointed  instru- 
ment). A  genus  founded  on  the  roots  of  various  species 
of  Sigillaria. 

STRATUM  (Lat.  stratus,  spread  out;  or  stratum,  a  thing  spread 
out).  A  layer  of  rock. 

STROMATOPORA  (Gr.  stroma,  a  thing  spread  out;  poros,  a  pas- 
sage or  pore).  A  Palaezoic  genus  of  Protozoa. 

STROPHOMENA  (Gr.  strophao,  I  twist;  wienf,  moon).  An  ex- 
tinct genus  of  Brachiopods. 

SUB-CALCAREOUS.     Somewhat  calcareous. 

SUB-CENTRAL.     Nearly  central,  but  not  quite. 

SUTURE  (Lat.  suo,  I  sew).  The  line  of  junction  of  two  parts 
which  are  immovably  connected  together.  Applied  to  the  line 
where  the  whorls  of  a  univalve  shell  join  one  another;  also 
to  the  lines  made  upon  the  exterior  of  the  shell  of  a 
chambered  Cephalopod  by  the  margins  of  the  septa. 

SYRINGOPORA  (Gr.  surigx,  a  pipe;  poros,  a  pore).  A  genus  of 
Tabulate  Corals. 


TABULA    (Lat.    tabula,   a   tablet).     Horizontal   plates   or   floors 

found   in    some    Corals,    extending   across    the    cavity    of   the 

"  theca  "  from  side  to  side. 
TEGUMENTARY   (Lat.  tegumentum,  a  covering).     Connected  with 

the  integument  or  skin. 
TELEOSAURUS    (Gr.   teleios,  perfect;  saura,  lizard).     An  extinct 

genus  of  Crocodilian  Reptiles. 
TELEOSTEI  (Gr.  teleios,  perfect;  osteon,  bone.)     The  order  of  the 

"  Bony  Fishes." 


414  GLOSSARY. 

TELSON  (Gr.  a  limit).  The  last  joint  in  the  abdomen  of  Crus- 
tacea; variously  regarded  as  a  segment  without  appendages,  or 
as  an  azygous  appendage. 

TENTACULITES  (Lat.  tentaculum,  a  feeler).  A  genus  of  Ptero- 
poda. 

TERERBRATULA  (Lat.  terebratus,  bored  or  pierced.)  A  genus  of 
Brachiopoda,  so  called  in  allusion  to  the  perforated  beak  of 
the  ventral  valve. 

TEST  (Lat.  testa,  shell.)  The  shell  of  Mollusca,  which  are  for 
this  reason  sometimes  called  "  Testacea,"  also,  the  calcareous 
case  of  Echinoderms;  also,  the  thick  leathery  outer  tunic  in 
the  Tunic  at  a. 

TESTACEOUS.     Provided  with  a  shell  or  hard  covering. 

TESTUDINJD^E  (Lat  tesiudo,  a  tortoise).  The  family  of  the  Tor- 
toises. 

TETRABRANCHIATA  (Gr.  tetra,  four;  bragchia,  gill).  The  order 
of  Cephalopoda  characterized  by  the  possession  of  four  gills. 

TEXULARIA   (Lat.  texilis,  woven).     A  genus  of  Foraminifera. 

THECA  (Gr.  the'ke,  a  sheath).     A  genus  of  Pteropods. 

THECODONTOSAURUS  (Gr.  theke,  a  sheath;  odous,  tooth;  saura, 
lizard).  A  genus  of  "  Thecodont "  Reptiles,  so  named  in  allu- 
sion to  the  fact  that  the  teeth  are  sunk  in  distinct  sockets. 

THERIODONT  (Gr.  tlrtrion,  a  beast;  odous,  tooth).  A  group _of 
Reptiles  so  named  by  Owen  in  allusion  to  the  Mammalian 
character  of  their  teeth. 

THORAX   (Gr.  a  breastplate).     The  region  of  the  chest. 

THYLACOLEO  (Gr.  thulakos,  a  pouch;  leo,  a  lion).  An  extinct 
genus  of  Marsupials. 

TRIGONIA  (Gr.  treis,  three;  gonia,  angle.)  A  genus  of  Bivalve 
Molluscs. 

TRIGONOCARPON  (Gr.  treis,  three;  gonia,  angle;  karpos,  fruit). 
A  genus  founded  on  fossil  fruits  of  a  three-angled  form. 

TRILOBITA  (Gr.  treis,  three;  lobos,  a  lobe).  An  extinct  order  of 
Crustaceans. 

TRINUCLEUS  (Lat.  iris,  three;  nucleus,  a  kernel.)  A  genus  of 
Trilobites. 

TROGONTHERIUM  (Gr.  trogo,  I  gnaw;  therion,  beast.)  An  extinct 
genus  of  Beavers. 

TUBICOLA  (Lat  tuba,  a  tube;  and  colo,  I  inhabit).  The  order  of 
Annelida  which  construct  a  tubular  case  in  which  they  protect 
themselves. 

TUBICOLOUS.     Inhabiting  a  tube. 

TUNICATA  (Lat.  tunica,  a  cloak).  A  class  of  Molluscoida  which 
are  enveloped  in  a  tough  leathery  case  or  "  test." 

TURBINATED  (Lat.  turbo,  a  top).  Top-shaped;  conical  with  a 
round  base. 

TURRILITES  (Lat.  turns,  a  tower).  A  genus  of  the  Ammoni- 
tida. 

U 

UMBO  (Lat.  the  boss  of  a  shield).     The  beak  of  a  bivalve  shell. 
UNGUICULATE  (Lat.  unguis,  nail).    Furnished  with  claws. 


GLOSSARY.  415 

UNGULATA  CLat.-*ungula,  hoof).  The  order  of  Mammals  com- 
prising the  Hoofed  Quadrupeds. 

UNGULATE.     Furnished  with   expanded  nails  constituting  hoofs. 

UNILOCULAR  (Lat.  unus,  one;  and  loculus,  a  little  purse.  Possess- 
ing a  single  cavity  or  chamber.  Applied  to  the  shells  of  Fora- 
minifera  and  Mollusca. 

UNIVALVE  (Lat.  unus,  one;  valvcc,  folding-doors).  A  shell  com- 
posed of  a  single  piece  or  valve. 

URODELA  (Gr.  our  a,  tail;  delos,  visible).  The  order  of  the  Tailed 
Amphibians  (Newts,  etc.). 

VENTRAL  (Lat.  venter,  the  stomach).  Relating  to  the  inferior 
surface  of  the  body. 

VENTRICULITES  (Lat.  ventriculum,  a  little  stomach).  A  genus 
of  siliceous  Sponges. 

VERMIFORM  (Lat.  vermis,  worm;  and  forma,  form).    Worm-like. 

VERTEBRA  (Lat.  verto,  I  turn).  One  of  the  bony  segments  of  the 
vertebral  column  or  backbone. 

VERTEBRATA  (Lat.  vertebra,  a  bone  of  the  back,  from  verier e,  to 
turn.)  The  division  of  the  Animal  Kingdom  roughly  character- 
ized by  the  possession  of  a  backbone. 

VESICLE  (Lat.  vesica,  a  bladder).     A  little  sac  or  cyst. 

W 

WHORL.  The  spiral  turn  of  a  univalve  shell. 

X 

XIPHOSURA  (Gr.  xiphos,  a  sword;  and  oura,  tail).  An  order  of 
Crustacea,  comprising  the  Limuli  or  King-Crabs,  characterized 
by  their  long  sword-like  tails. 

XYLOBIUS  (Gr.  xulon,  wood;  bios,  life).  An  extinct  genus  of 
Myriapods,  named  in  allusion  to  the  fact  that  the  animals  lived 
on  decaying  wood.  / 


ZAPHRENTIS  (proper  name).    A  genus  of  Rugose  Corals. 

ZEUGLODONTID^E  (Gr.  zeugle',  a  yolk;  odous,  a  tooth).  An  extinct 
family  of  Cetaceans,  in  which  the  molar  teeth  are  two-fanged, 
and  look  as  if  composed  of  two  parts  united  by  a  neck. 

ZOOPHYTE  (Gr.  coon,  animal;  phuton,  plant).  Loosely  applied 
to  many  plant-like  animals,  such  as  Sponges,  Corals,  Sea- 
anemones,  Sea-mats,  etc.). 


INDEX. 


Acadian  Group,  79. 

Acer,  320. 

Acervularia,  121, 176. 

Acidaspis,  126. 

Acorn-shells,  275. 

Acroculia,  130. 

Acrodus,  220,  249,  283 ;  nobilis,  249. 

Acrotreta,  112. 

Acroura,  122. 

Actinocrinus,  178. 

jEglina,  110. 

jEpiornis,  361. 

Agnostus,  85-87, 109;  rex,  85. 

^4  ices  male  his,  368. 

^Zecfo,  110. 

Alethopteris,  138, 167,  200. 

^4Za#  (see  Sea- weeds). 

Alligators,  224,  307. 

.4Znws,  270. 

Amblypterus,  192 ;  macropterus,  192. 

Ambonychia,  112. 

Ammonites,  191,  218-220,  244-246,  280; 
Humphresianus,  245;  bifrons,  245. 

Ammonitidse,  246,  280,  294,  304. 

Amphibia,  193;  of  the  Carboniferous, 
193-195;  of  the  Permian,  204;  of  the 
Trias,  221-223 ;  of  the  Jurassic,  249 ; 
of  the  Miocene,  324. 

Amphicyon,  333. 

Amphilestes,  261. 

Amphispongia,  120. 

Amphistegina,  322. 

Amphitherium,  261,  262;  Prevostii.  261. 

Amphitragulus,  328. 

_<4rapZea;w»,  177;  coralloides,  178. 

Ampyx,  110. 

Ananchytes,  275. 

Anchitherium,  311,  312. 

Ancyloceras,  280,  281 ;  Matheronianus, 
281. 

Ancylotherium  Pentelici,  326. 

Andrias  Scheuchzeri,  324,  325. 

Anglosperms,  269,   271. 

Animal  Kingdom,  divisions  of,  389- 
392. 

Anisopus,  211. 

Annelida,  of  the  Cambrian  period, 
82,  84 ;  of  theiLower  Silurian  109 ;  of 
the  Upper  Silurian,  124, 125;  of  the 
Devonian,  146,  147;  of  the  Carbon- 
iferous, 181. 


Annularia,  139,  200,  212. 

Anomodontia,  226. 

Anoplotheridse,  313. 

Anoplotherium,  813 ;  commune,  313. 

Ant-eaters,  309,  326,  363,  364,  366. 

Antelopes,  328. 

Anthracosaurus,  Russelli,  194. 

Ahthrapalaemon  gracilis,  184. 

Antilocapra,  330. 

Antilope  quadricornis,  320. 

Antwerp  Crag,  336. 

Apes,  334. 

Apiocrinus,  238. 

Apteryx,  359,  361. 

Aqueous  rocks,  15. 

Arachnida  of  the  Coal-measures,  185, 

Aralo-Caspian  Beds,  337. 

Araucaria,  270. 

Araucarioxylon,  173. 

Jrra,  203;  anliqua,  203. 

Archseocidaris,  182. 

Archseocyathus ,  82. 

Archseopteryx,  260,  290;  macrura,  259 

260. 

Archxosphserinse,  75. 
Archimedes.  187 ;  Wortheni,  187. 
Arhciulus,  185. 

Arctic  regions,  Miocene  flora  of,  321. 
Arctocyon,  315. 
Arenaceous  rocks,  21. 
Arenicolites,  83;  didymus,  88. 
Arenig  rocks,  93,  95. 
Argillaceous  rocks,  21. 
Armadillos,  309,863,  366. 
Artiodactyle  Ungulates,  313,  328. 
Asaphus,  110;tyranmts,  108, 110. 
Ascoceras,  132. 
Aspidella,  76. 
Aspidura  loricata.  215. 
Astarte  borealis,  351. 
Asterophyllites,  139,  200. 
Asterosteus,  153. 
^sfranda?,  238. 
Astrxospongia,  120, 141. 
Astylospongia,  99;  prxmorsa,  99. 
Athyris,  112, 130, 149,202;  subtil ita,189. 
Atlantic  Ooze,  23, 24. 
Atrypa,  130:  congcsta,  129;  hemisphx- 

rica,  130 ;  reticularis,  149, 150. 
Auger-shells.  303. 
Aurochs,  370. 


(416) 


INDEX. 


417 


Aves  (see  Birds). 

Avicula,  242 ;  contora,  216, 217 ;  socialis, 

217. 

"Avicula  contorta  Beds,"  209,  217. 
Aviculidx,  203,  277. 
Aviculopecten,  190. 
Axophyllum,  176. 
Aymestry  Limestone,  117, 119. 
Azoic  rocks,  67. 

Baculites,  281 ;  anceps,  282. 

Bagshot  and  Bracklesham  Beds,  297. 

Bakewellia,  203. 

Balxna,  326. 

Bala  Group,  93,  95. 

Bala  Limestone,  94. 

Balanidas,  275. 

Banksia,  270.  320. 

Barbadoes  Earth,  34. 

Barnacles,  275. 

Bath  Oolite.  234. 

Bats,  315,  334. 

Bears,  342,  373. 

Beaver,  334,349. 

Beetles,  185,  322. 

Belemnitella  mucrnnata,  283. 

Belemnites,  219,  247,  283;  canaliculatus, 
248. 

Belemnitidff,  247,  294. 

Belemnotevthis,  247. 

Belinurus,  182. 

Bellerophon,  113,131,  151,193;  Argo.llZ. 

Belodon,  224 ;  Carolinensis,  225. 

Belosepia,  305. 

Beloteuthis  subcostata,  247. 

Bembridge  Beds,  297. 

Beryx,  284 ;  Lewesiensis,  284. 

Bcyrichia,  108;  complicata,  108. 

Bird's  eye  Limestone,  96,97. 

Birds,  of  the  Trias,  228;  of  the  Juras- 
sic, 259-261;  of  the  Cretaceous,  289, 
290;  of  the  Eocene, 307;  of  the  Post- 
Pliocene,  358-361. 

Bison  prisons,  370. 

Bituminous  Schists  of  Caithness,  37. 

Bivalves  (see  Lamellibranchiata). 

Black-lead  (see  Graphite). 

Black-River  Limestone,  96,97. 

Blastoidea,  179;  of  the  Devonian,  145; 
of  the  Carboniferous,  179. 

Boidse,  306. 

Bolderberg  Beds,  317. 

Bone-bed,  of  the  Upper  Ludlow,  118; 
of  the  Trias,  230. 

Bony  Fishes  (see  Teleostean  Fishes). 

Bos  primtgenius,  36Q;  taunts,  369. 

Boulder-clay,  350. 

BourgueUcrinus,  274. 

Bovey- Tracy  Beds,  316,  320. 

Brachiopoda,  127;  of  the  Cambrian 
rocks,  87  ;of  the  Lower  Silurian ,  109- 
11 1;  of  the  Upper  Silurian.  127-130; 
of  the  Devonian,  149,  150;  of  the  Car- 
boniferous, 188-190 ;  of  the  Permian, 
202;  of  the  Trias,  216;  of  the  Juras- 
sic, 241 ;  of  the  Cretaceous,  267;  of 
the  Eocene.  302. 

Bnehymetopug,  183. 

Brachyurous  Crustaceans,  184,  202. 

Bradford  Clay,  234. 

Breaks  in  the  Geological  and  Pal- 
seontological  record,  45-53. 


Breccia,  20. 

Brick-earths,  352. 

Bridlington  Crag,  336,  337,  349. 

Brittle-stars  (s^eOphiuroidea). 

Bronteus,  146. 

Brontothcridte,  327. 

Brontotherium  ingens,  327. 

Brontozoum,  211. 

Buccinum,  244. 

Bucklandia,  237. 

Bulimus,  304. 

Bunter  Sandstein,208,  209,  211. 

Butterflies,  241,  322. 

Byssoarca,  203. 


Cainozoic  (see  Kainozoic). 

Calamaries,  247. 

CalamiteSj  167,   168,  200;  cannsrformia, 

169. 

Calcaire  Grossier,  297,  298. 
Calcareous  rocks,  21-83;  Tufa,  22. 
Calciferous  Sand-rocK,  96,  97. 
Calveria,  181. 

Calymene,  110, 126:  Blumcnbachii,  108. 
Camarophoria  globulin  a  202. 
Cambrian  period.  77-91;  rocks  of,  in 

Britain,  77,  78;  in  Bohemia  79;  in 

North  America,  79;  life  of,  80-91. 
Ccanelopardalidx,  328. 
Camels,  328,  368. 
Cam's  lupus,  319;  Parisiensis,  315. 
Caradoc  rocks,  93,  95,  97. 
Carbon,  origin  of,  37. 
Carboniferous  Limestone,  161, 162. 
Carboniferous  period,  160-193;  rocks 

of,  160-163 ;  life  of,  163-192. 
Carboniferous  Slates  of  Ireland,  137, 

161, 162. 

Carcharias,  283. 

Carcharodon,  ZQ5,323;productus,  324. 
Cardinia,  242. 
Cardiocarpon,  139. 
Cardiola,  130 ;  fibrosa,   130 ;  interrupts, 

130. 

Cardita,  219,  30^;  planicosta,  302,  303. 
Cardium,  302 ;  Rhxticum,  216,  217. 
Caribou,  369. 
Carnivora,  of  the  Eocene,  315;  of  the 

Miocene,  333:  of  the  Pliocene,  341, 

342;  of  the  Post-Pliocene,  373-375. 
Caryocaris,WS,  109. 
Caryoerinus  ornatus,  107. 
Castor  fiber,  349. 
Castoroides  Ohioensis.  375. 
Catastrophism,  theory  of,  3. 
Catopterus,  220. 
Cauda-Galli  Grit.  137,139. 
Caulopteris,  138, 167. 
Cave-bear,  373. 

Cave-deposits,  350,  352,  354,  356. 
Cave-hyaena,  374. 
Cave-lion,  375. 
Caves,  formation  of,  354 ;  deposits  in, 

356. 

Cavicornia,  329. 
Cement-stones,  32. 
Cephalaspis,  154. 
Cephalopoda,  of  the  Cambrian  period, 

89;  of  the  Lower  Silurian,  1  3-116; 

of  the  Upper  Silurian,  132;  of  the 

Devonian,  151 ;  of  the  Carbonifer- 


4i8 


INDEX. 


ous,  189.  191;  of  the  Permian,  203; 
of  the  Trias.  217;  of 'the  Jurassic, 
246-249;  of  the  Cretaceous,  280-2<^3; 
of  Eocene,  304 ;  of  the  Miocene,  323. 

Ceratiocaris,  109. 

Ceratitcs,  218-219;  nodosus  218. 

Ceratodun,  220;  attus,  220;  Fosteri,  220, 
221,  2(52 ;  scrratus,  220. 

Ceriopora,  148;  Hamiltonensis,  148. 

Ceritnium,  219,  303 ;  hexagonum,  304. 

Cervidx,  of  the  Miocene  period,  328; 
of  the  Pliocene,  340;  of  the  Post- 
Pliocene,  368,  369. 

Cervus,  328 ;  capreolus,  349,  368 ,  elaphus, 
349,  368;  megaceros,  368;  tarandus, 
368. 

Cestracinn  Philippi,  192,  262. 

Cestracionts,  of  the  Devonian,  156; 
of  the  Carboniferous,  192;  of  the 
Permian,  203;  of  the  Trias,  220;  of 
the  Jurassic,  252;  of  the  Creta- 
ceous, 283. 

Cetacea,  309;  of  the  Eocene,  309;  of 
the  Miocene,  326. 

Cetiosaurus,  256,  257. 

Chxropotamus,  313. 

Chce,tctes,  106,  177 ;  tumidus  178. 

Chain-coral,  121. 

Chalk,  267;  structure  of,  22-24 ;  fora- 
minifera  of,  26,  272;  origin  of,  24; 
with  flints,  267;  without  flints,  267. 

Chama,  243. 

Chamcerops,  319;  Helvetica,  319. 

Chazy  Limestone,  96,  97. 

Cheiroptera,  of  the  Eocene,  315,  316;  of 
the  Miocene,  334. 

Cheirotherhim,  221,  222. 

Cheirurus,  110,  126;   bimucronatus,  126. 

Chelichnus  Duncani,  207. 

Chelone  Benstedi,  289;  planiceps,  260. 

Chelonia,  of  the  Permian,  207;  of  the 
Jurassic,  259;  of  the  Cretaceous, 
289 ;  of  the  Eocene,  306. 

Chcmnitzia,  219. 

Chemung  Group,  137,  138, 139. 

Chert,  35. 

Chillesford  Beds,  336,  338,  349. 

Chonetes,  130,  149, 188;  Hardrensis,  189. 

Chonophyllum,  176. 

Ciclaris,  275. 

Cincinnati  Group,  96,  97. 

Cinnamomum  polymorphum,  320. 

Cinnamon-trees,  270,  300,  316,  320. 

Cladodus,  192. 

Claibome  Beds,  299. 

Clathropora,  148;  intertexta,  148. 

Clay,  21;  Red,  origin  of,  36. 

Clay-ironstone,  nodules  of,  32. 

Cleidophorns,  112. 

Cleodora,  323. 

Climacograptus,  103,  121. 

Clinton  Formation,  118, 119. 

Clisiophyllum,  177. 

Clupeidse,  284. 

Clymenia,  52;  Scdawickii,  151. 

Coal,  37;  structure  of,  166;  mode  of 
formation  of,  16>. 

Coal-measures,  12,  163;  mineral 
characters  of.  162  ;  mode  of  forma- 
tion of.  163.  165;  plants  of,  167-173. 

Coccoliths,  269. 

Coccosteus,  153,  154. 


Cochiiodus,  192:  contortus,  193. 

Coleoptera,  185,  322. 

Colossochelys  Atlas,  324. 

Columnaria,  106;  alveolata,  106. 

Comatula,  239,  274. 

Conclusions  to  be  drawn  from  Fos- 
sils, 53-58. 

Concretions,  calcareous,  31;  phos- 
phatic,  32;  of  clay-ironstone,  32;  of 
manganese,  33. 

Conglomerate,  19. 

Coniferse,  270;  wood  of,  14;  of  Devon- 
ian period,  140;  of  the  Carbonifer- 
ous, 174;  of  the  Permian,  200;  of  the 
Trias,  213;  of  the  Jurassic  period, 
237. 

Coniston  Flags  and  Grits,  117. 

Connecticut  Sandstones,  footprints 
of,  228,  360. 

Conocoryphe  Mathcwi,  85;  Sultzeri,  85. 

Conodonts,  116,  133. 

Constellaria,  106. 

Constricting  serpents  of  the  Eocene, 
306. 

Contemporaneity  of  strata,  45-47. 

Continuity,  theory  of,  5-8. 

Conularia,  112,  131,  151,  190,  203,  244;  or- 
nata,  151. 

Conulus,  190. 

Convs,  803. 

Coomhola  Grits,  161,  162. 

Coprolites,  32,  250. 

Coralline  Crag,  335. 

Corallines,  26. 

Coralliitm,  322. 

Coral-rag,  2K4,  237,  238. 

Coral-reefs,  25-28. 

Coral-rock,  27. 

Coral-sand,  20,  27. 

Corals,  104;  of  the  Lower  Silurian, 
1(K  107;  of  the  Upper  Silurian,  122; 
of  the  Devonian,  142-145;  of  the 
Carboniferous,  176-178;  of  the  Per- 
mian, 201;  of  the  Trias,  214;  of  the 
Jurassic,  235, 237;  of  the  Cretaceous, 
274;  of  the  Eocene,  302;  of  the  Mio' 
cene,  322. 

Corbula,  242. 

Cornbrash.  234,  235. 

Corniferous  Limestone,  137,  139. 

Cornulites,   12-x 

Cornus,  27o. 

Coryphodon,  310. 

Cowries,  267,  280.  303. 

Crabs,  184,  20J.  240,  275. 

Crae,  Red,  335;  White,  335;  Norwich, 
336;  Antwerp.  33C:  Bridlington,  336; 
Coralline,  335. 

Crania,  112,  129,  202,  277;  Ignaber gen- 
sis.  277. 

Crassatella,  302. 

Crepiflophyllum,  141;  Archiaci,  144. 

Cretaceous  period,  264-292;  rocks  of, 
in  Britain,  264-267;  in  North  Amer- 
ica 268.  269;  life  of,  2(19-292. 

Crinoidal  Limestone,  25,  26. 

Crinoidea,  123;  of  the  Cambrian,  82; 
of  the  Lower  Silurian,  106;  of  the 
Upper  Silurian,  122-124;  of  the  De- 
vonian, 145;  of  the  Carboniferous, 
177;  of  the  Permian,  201;  of  the 
Trias,  215;  of  the  Jurassic,  238;  of 


INDEX. 


419 


the  Cretaceous,  274;  of  the  Eocene, 
302. 

Crioceras,  281;  cristatum,  282. 

Crocodilia,  224;  of  the  Trias,  224;  of  the 
Jurassic,  259;  of  the  Cretaceous, 
289;  of  the  Eocene,  307. 

Cromer  Forest-bed,  348. 

Crossozamites,  237. 

Crotalocrinus,  125. 

Crustacea,  of  the  Cambrian,  84-88;  of 
the  Lower  Silurian,  108,  109;  of  the 
Upper  Silurian,  i25-126-  of  the  De- 
vonian, 146,  148;  of  the  Carbonifer- 
ous, 182-185;  of  the  Permian,  201; 
of  the  Trias,  215;  of  the  Jurassic, 
240,  of  the  Cretaceous,  275. 

Cryptogams,  167,  270. 

Ctenacanthus,  192, 

Ctenodonia,  112. 

Cupressus,  270. 

Cursores,  307,  359. 

Cuttle-fishes  (see  Dibranchiate  Cep- 
halopods). 

Cyathocrinus,  178. 

Cyathophyllirm,  121,  144, 177. 

Cycadopteris,  270. 

Cycads,  213;  of  the  Carboniferous, 
174;  of  the  Permian,  201;  of  the 
Trias,  213;  of  the  Jurassic,  237;  of 
the  Cretaceous,  270. 

Cyclas,  277. 

Cyclonema,  131, 

Cyclophthalmus  senior,  185. 

C'yclostoma,  304;  Arnotldii,  304. 

Cynodraco,  226. 

Cyprsea,  280,  303;  cleganx,  303. 

Cypress,  270.  320,  322. 

Cypridina,  146. 

Cypridina  Slates. 

Cyrena,  242,  277,  802. 

Cyrtina,  219.  220. 

Cyrtoceras,  115. 

Cysttphyllum,l2l,  144,  \1S\vesiculosum, 
143. 

Cystoidea,  106-109;  of  the  Cambrian, 
82;  of  the  Lower  Silurian,  108;  of 
the  Upper  Silurian,  122. 


Dachstein  Beds,  210,  211. 

Dadoxylon,  140,  173. 

Daonella,  216;  Lommelli,  216. 

Dasornis  Londinensis,  307. 

Decapod  Crustaceans,  183. 

Deer,  328,  340,  368. 

Deinosauria,  255;  of  the  Trias,  227;  of 
the  Jurassic,  255-258;  of  the  Creta- 
ceous, 285-287. 

Deinotherium,  331,  332;  giganteum.  331. 

Denbighshire  Flags  and  Grits,  117. 

Dendrocrinus,  82. 

Dendrograptus.  101. 

Desmids,  141,  269. 

Devonian  Formation,  135-139:  origin 
of  name,  135;  relation  to  Old  Red 
Sand-stone,  135-136;  of  the  Devon- 
shire, 135;  of  Nc-'-th  Ame.ica,  135, 
136;  life  of,  137-158. 

Diadema,  275. 

Diatoms,  34;  of  the  Devonian,  140;  of 
the  Carboniferous,  167;  of  flints, 
269;  of  Richmond  Earth,  34,  318. 


Dibranchiate  Cephalopods,  114;  of 
the  Trias,  217;  of  the  Jurassic,  244- 
246;  of  the  Cretaceous,  283,  284;  of 
the  Eocene,  805;  of  the  Miocene, 
323. 

Dicer  as,  243;  arietina,  243. 

Diceras  Limestone,  234,  243. 

Dichobune,  313. 

Dichograptus,  102;  octobrachiatus,  102. 

Dicotyledonous  plants,  270. 

Dicotyles  antiquus,  328. 

Dicranograptus,  103,  121. 

Dictyonema,  89,  101,  \1\\sociale,  89. 

Dicynodon,  227;  lacerticeps,  226. 

Didelphys,  262,  326;  gypsorum,  309. 

Didus  ineptus,  361. 

Didymograptus,  102;  divaricatus,  103. 

Dikellocephalus  Celticux,  85;  Minneso- 
tensis,  85. 

Dimorphodon,  254. 

Dinichthys,  155;  Hertzeri,  154. 

Dinoceras,  314;  mimbilis,  314. 

Dinocerata,  314. 

Dinophis,  306. 

Dinornis,  359,    360;   elephantopus,  360 ; 


giganteiis,  361. 

)inf>nauria 


Dinosauria  (see  Dcinosauria). 

Dinotherium  (see  Deinotherium). 

Diphyphyllum,  144. 

Diplograptus,  103, 121;  prisiis,  103. 

Dipnoi,  156,  196,  221. 

Diprotodon,  362;  australis,  362. 

Diptera,  322. 

Discina,  88,  112, 12p,  202. 

Discoidea,  275;  cylindrica,275. 

Dithyrocaris,  183;  Scouleri.  184. 

Dodo,  361. 

Dog-whelks,  303. 

Dolomite,  29. 

Dolomitic  Conglomerate  of  Bristol, 

206,  225. 

Dolphins,  309,  326. 
Dorcathcrium,  328. 
Downton  Sandstone,  117. 
Draco  volans,  252. 
Dragon-flies  322. 
Drift,  Glacial,  349. 
Dremotherium,  328. 
Dromatherium  sylvestre,  229, 231. 
Dryandra,  270. 
Dryopithecus,  334. 
Dugongs,  309. 

Echinodermata,  of  the  Cambrian,  82; 
of  the  Lower  Silurian,  106;  of  the 
Upper  Silurian,  122;  of  the  Devon- 
ian, 145;  of  the  Carboniferous,  177; 
of  the  Permian,  200:  of  the  Trias, 
214;  of  the  Jurassic,  238;  of  the  Cre- 
taceous, 274;  of  the  Eocene,  302. 

Echinoidea,  180;  of  the  Upper  Silu- 
rian, 122;  of  the  Devonian,  145;  of 
the  Carboniferous,  181;  of  the  Per- 
mian, 201;  of  the  Jurassic,  240;  of 
the  Cretaceous,  274. 

Edentata,  363;  of  the  Eocene,  309;  of 
the  Miocene,  326;  of  the  Post-Plio- 
cene, 363-367. 

Edriocrinus,  125. 

Eifel  Limestone,  137. 

Elasmobranchii  (see  Placoid  Fishes). 

Elasmosaiirus,  285. 


42O 


INDEX. 


Elephants,  331,  332,  341. 

Elephas,  341;  Americanus,  371;  anti- 
quus,  341,  342,  349,  354,  370;  Falcon- 
eri,  373;  Melitensis,  373;  meridiona- 
lis,  341,  349,  370;  planifrons,  332; 
primigenius,  352,  354,  369,  370. 

Elk,  868;  Irish,  368,  369. 

ElUpsocephalus  Hoffi,  85. 

Elotherium,  328. 

Emydidse,  306. 

Emys,  289. 

Enaliosaurians,  225,  249,  286. 

Encrinital  marble,  25. 

Encrinurus,  126. 

Encrinus  liliiformis,  215. 

Endogenous  plants,  270. 

Etidophyllum  176. 

Endothyra,  175;  Bailyi,  175. 

Engis  skull,  377. 
' 


Entomoconchus  Scouleri,  183,  184. 
Eocene  period,  294;  rocks  of,  in  Brit- 

ain,   296,    297;    in    France,  297;   in 

North  America,    298,  399;  life  of, 

299-316. 

Eocidaris,  201. 
Eophyton,  81;  Linneanum,  81. 
Eophyton  Sandstone,  79. 
Eosaurus  Acadianus,  195. 
Eozoic  rocks,  67. 
Eozoon  Bavaricum,  76. 
Eozoon  Canadense,  68,  76;  appearance 

of,  in  mass,  69;  minute  structure 

of,   70,  71;  affinities  of,  with  For- 

aminifera,  72-73. 
Ephemeridse,  147. 
Equidx,  311,  312,  327,  340. 
Equisetacese,  168. 
Equisetites,  200. 
Equus,  312;  caballus,  367;  excelsus,  340; 

fossilis,  349,  367. 
Eridophyllum,  144. 
Eryon,  arctiformis,  240,  241. 
Eschara,  277. 
Escharidse,  277. 
Escharina,  277;  Oceani,  277. 
Estheria,  147,  183,  215;  te?ie«a,  184. 
Eucalyptocrinus,  124;  polydactylus,  124. 
Eucladia,  122. 
Euomphalus,  130,  151,  190,  203,  219-  dts- 

oors,  131. 
Euplectclla,  273. 
Eitproops,  182. 
European  Bison,  370. 
Eurypterida,    126,    182;  of  the    Upper 

Silurian,  126;  of  the  Devonian,  146. 
Even-toed  Ungulates,  310,  328,  367. 
Exogenous  plants,  270. 
Exogyra,  243;  virgula,  243. 
Extinction  of  species,  58,  59. 

Fagus,  270. 

Faluns,  317. 

Fan-palms,  319. 

Favistella,  106. 

Parasites.    121.    145;   Gothlandica,  145; 

hemisphasrica,  145. 
Faxoe  Limestone,  267,  295. 
.Fefa's  au<7ws/r/.s,342;  Zeo,  375;speZcea,374. 
Fenestella,  110,   127,   148,   187,  202,  216; 

cribrosa,    148;  magnified,    148;   re#- 

jormis,  202. 


Ferns,  of  the  Devonian,  136;  of  the 
Carboniferous,  167;  of  the  Permian, 
200;  of  the  Trias,  212;  of  the  Juras- 
sic, 236;  of  the  Cretaceous,  269. 

Fig-shells,  303. 

Fishes,  152;  of  the  Upper  Silurian, 
132,  133;  of  the  Devonian,  152-157;  of 
the  Carboniferous,  191,  192;  of  the 
Permian,  204,  205;  of  the  Trias,  219, 
220;  of  the  Jurassic,  247-249;  of  the 
Cretaceous,  283,  285;  of  the  Eocene, 
305,  306;  of  the  Miocene,  323,  324. 

Flint,  31:  structure  of,  35;  origin  of, 
34;  organisms  of,  36,  141,  271;  of 
Chalk,  35,  266,  269. 

Flora  (see  Plants). 

Footprints  of  Cheirothcrium,  221,  222; 
of  the  Triassic  sandstones  of  Con- 
necticut, 228. 

Foraminifera,  23-25,  71-74;  of  the  Cam- 
brian, 82;  of  the  Lower  Silurian, 
93;  of  the  Carboniferous,  174, 176;  of 
the  Permian,  201;  of  the  Trias,  214; 
of  the  Jurassic,  237;  of  the  Creta- 
ceous, 22,  23,  271;  of  the  Eocene, 
300;  of  the  Miocene,  322;  of  the 
Post-Pliocene,  350;  of  Atlantic 
ooze,  22,  24;  as  builders  of  lime- 
stone, 25,  26,  30;  as  forming  green 
sands,  36. 

Forbesiocrinus,  179. 

Forest-bed  of  Cromer,  348. 

Forest-bugs,  322. 

Forest-marble,  234. 

Formation,  definition  of,  19;  succes- 
sion of,  43. 

Fossiliferous  rocks,  15-38;  chrono- 
logical succession  of,  38-45. 

Fossilization,  processes  of,  12-13. 

Fossils,  definition  of,  11;  distinctive, 
of  rock-groups,  39;  conclusions  to 
be  drawn  from,  53-58;  biological 
relations  of,  58-62. 

Foxes,  315. 

Fringe-finned  Ganoids,  156. 

Fucoidal  Sandstone,  79,  80. 

Fucoids,  80,98. 

Fuller's  Earth,  234,  236. 

Fusulina,  175:  cylindrica,  176. 

Fusus,  244,  303. 

Galeocerdo,  323. 

Galerites,  275;  albogalerus,  275. 

Galestes,2fi2. 

Ganoid  Fishes,  152;  of  the  Upper 
Silurian,  132;  of  the  Devonian,  152- 
155;  of  the  Carboniferous,  191,  192; 
of  the  Permian,  202;  of  the  Trias, 
219;  of  the  Jurassic,  249;  of  the  Cre- 
taceous, 283;  of  the  Eocene,  305, 

Gaspe  Beds,  135. 

Gasteropoda,  of  the  Cambrian,  89;  of 
the  Lower  Silurian,  113;  of  the  Up- 
per Silurian,  130,  131;  of  the  De- 
vonian, 150;  of  the  Carboniferous, 
190;  of  the  Permian,  204;  of  the 
Trias,  218;  of  the  Jurassic,  244,  245; 
of  the  Cretaceous,  279;  of  the 
Eocene.  303. 

Gastornis  Parisiensis  307. 

Gault,  264,  267. 


INDEX. 


421 


pper  Silurian,  120,  121. 
Oolite,  2S4,  236;  Upper,  264,  266, 


Gavial,  260,  307. 

Genesee  Slates,  137. 

Geological  record,  breaks  in  the,  48- 

56. 

Giraffes,  328. 
Glacial  period,  33o;  deposits   of,   349, 

3oO. 

Glandulina,  322. 
Glaucouite,  3f>,  74,  271. 
Glaucojiomr,  127,  187;  piilcherrima,  187. 
Globe  Crinoids  (*<'<  Cystoidea). 
Globigerina,23,  24,  272. 
Glutton,  374. 
Glyptaster,  122. 
Glyptocrinus,  125. 
Gtyptodon,  3«5.3G6;  davipcs,  366. 
Glyptolcemus,  156. 
Goats,  329. 

Goniatltes,  132,  151,  191,  219;  Jossx,  191. 
Gorffonidse,  302. 
Grallatores,  ."07. 
Graphite,  37;  mode  of  occurrence  of, 

37.  68;  origin  of,  37. 
Qraptolites,  90,  101;  structure  of,  101  ; 

of  the  Lower  Silurian,   101-104;  of 

the  U 
Great 

268. 

Greenland,  Miocene,  plants  of,  321. 
Greensand,  Lower,  264,  268. 
Greensands,  origin  of,  265. 
Grevillea,  270,  320. 
GriffltMdes,  183. 
Grizzly  Bear,  373. 
Ground  Sloths,  364. 
Gryphoen,  243;  incurva,  243. 
•Guelph  Limestone,  119. 
Gulo  ftttCttt,  374  ;  spelivux,  373. 
Guttenstein  Beds,  210,  211. 
Gymnospermous  Exogens,  270. 
Gypsum,  33,  197,  209. 
Gyracanthv*.  192. 
G'yroccras,  132. 

JIadrosaurus,  287. 

Jfdli.fhcrium,  309. 

Hallstadt  Beds,  210,  211. 

Halobia,  216. 

Hatysitcx,  121;  agglomerata,'122;  eaten- 

Ktarid,}22. 

Hamilton  formation,  137,  139. 
Hamites,  281  ;  rotundus,  282. 
Haplophlcbium  Barnesi,  186. 
Harlech  Grits,  78.  79. 
Harpes,  110,  126  ;  ungula,  126. 
Hastings  Sands,  265. 
Headon  and  Osborne  series,  297,  298. 
Heart-urchins,  322. 
Hcliolites,  106,  121,  274. 
Heliophyttum.  144,   176;  exiguum,  143. 
Helix,  304. 

Helladotherium,  328. 
Heloporafragilis,  128. 
Hemicidaris  crenularis,  240. 
Hemiptera,  322. 

Hemitrochizcvs  paradoxus,  202. 
Hempstead  Beds,  316. 
Hespe,rornis,29Q,  291;  regroftft,  29L 
Heteropoda,  112;  of  the  Lower  Silu- 

rian,  112;  of  the  Upper  Silurian, 

131  ;  of  the  Devonian,   150;  of  the 

Carboniferous,  lcJ9. 


Hinnites,  219. 

Hipparion,  312,32^,340. 

Hippodium,  242. 

Hippopotamus,    313;    amphibius,   328. 

340;  major,  3  11,  349,  367;   Sivalensis, 

329. 

Ifippothoa,  110. 
Hippurite  Marble,  278. 
Hlppuritcs,  278;  Toucasiana,  279. 
Hippuritidse,  278,  294. 
Histioderma,  83. 

Hollow-horned  Ruminants,  329. 
Holocystis  elegans,  274. 
Holopea,  131  ;  subconica,  131. 
Holopella,  131,219;  obsolcta,  131. 
Holoptychius,  156  ;  nobilisstmun,  158. 
Holostomatous  Univalves,  244,  303. 
Holothurians,  122. 
Holtcnia,  272. 
Homacant  tuts,  192. 
Homalonotus,  126,  146  ;  armatus,  147. 
Homo  diluvii  testis,  324. 
Honeycomb  Corals,  144. 
Hoofed  Quadrupeds,  310. 
Hudson  River  Group,  96. 
Human  implements  associated  with 

bones    of   extinct    Mammals,  377, 

378. 

Huronian  Period,  75,  76;  rocks  of,  75. 
Hysena  crocuta,  342  ;  spelsea,  374  ;  Hip- 

parionum,  342. 


Hysenodon,  315. 
Hyalea  D'Orbir/nyana,  323. 
Hybodus,  2  0,  249,  283. 
Hydractinia,  273. 
Hydroid  Z9Ophytes,  104,  273. 
Hymenocaris  vermicauda,  84,  85. 
Hymenophyllites,  167. 
Hyme.noptera,  322. 
Hyopotamus,  313. 
Hyperodapedon,  224. 
Hypsiprymnopsis,  230. 
Hystrix  primigenius,  333. 


Ichthyocrinus  leevis,  125. 

IcMhyornis,  290,  291  ;   dispar,  290,  291. 

Ichthyosaurus,  249,  250,  285;  communis, 

249. 

Ictitherium,  333. 
Iguana,  286. 

Iguanodon,  2C6,  287;  Mantelli,  286. 
Ilfracombe  Group,  136. 
Illsenus,  110,  126. 
Imperfection    of  the  palseontologi- 

cal  record,  52,  53. 
Inferior  Oolite,  234,  236. 
Infusorial  Earth,  35. 
Inocerarmis,  277 ;  sitlcatus,  278. 
Insectivora'ot  the  Eocene,  316;  of  the 

Miocene,  354. 
Insects  of  the  Devonian,  147;  of  the 

Carboniferous,  186;  of  the  Jurassic, 

240;  of  the  Miocene,  322, 323. 
Irish  Elk,  360. 
Ischadites,  100,  120. 
Isopod  Crustaceans,  84. 

Jackson  Beds,  299. 

Jurassic  period,   232;  rocks  of,  333; 
life  of,  236,  263. 


422 


INDEX. 


Jfaidacarpum,  237. 

Kainozoic  period,  45,  294-296. 

Kangaroo,  362. 

Kelloway  Rock,  234. 

Kent's  Cavern,  deposits  in,  356. 

Keuper,  209,  211. 

Kimmeridee  Clay,  234,  239. 

King-crabs,  84, 126,  1/7,  182. 

Koninckia,  219. 

Kossen  Beds,  210,  211. 

Labyrinthodon  Jcegeri,  223 

Labyrinthodontia,  194;  of  the  Carbon- 
iferous, 19:M95;  of  the  Permian, 
204;  of  the  Trias,  221-223. 

Lace-corals,  110,  127,  148,  186,  202,  216. 

Lacertilia,  206;  of  the  Permian,  205, 
206;  of  the  Trias,  223,  224;  of  the 
Jurassic,  259;  of  the  Cretaceous, 
288. 

Lxlaps,  287. 

Lamellibranchiata,  of  the  Cambrian, 
89;  of  the  Lower  Silurian,  112;  of 
the  Upper  Silurian,  130;  of  the  De- 
vonian, 150 ;  of  the  Carboniferous, 
190;  of  the  Permian.  202;  of  the 
Trias,  216;  of  the  Jurassic,  242-244; 
of  the  Cretaceous,  276-278;  of  the 
Eocene,  302. 

Lamna,  283,  323. 

Lamp-shells  (see  Brachiopoda) . 

Land-tortoises,  324. 

Lauracete,  320. 

Laurentiau  period,  65 ;  rocks  of,  65, 
66;  Lower  Laurentiau,  60;  Upper 
Laurentian,  66;  areas  occupiedby 
Laureutian  rocks,66;  limestones  of, 
66,  67 ;  iron-ores  of,  68 ;  phosphate 
of  lime  of,  68;  graphite  of,  68;  life 
of,  67-75. 

Leaf- beds  of  the  Isle  of  Mull,  316. 

Leda,  302;  truncata,  351. 

Leguminosites  Marcouanus,  271. 

Lemming,  358,  359. 

Lepadidx,  275. 

Lepadncrimw  Gebhardi,  107. 

Leperditia,  109;  canadensis  108. 

Lepidaster,  122. 

Lepidechinus,  181. 

Lepidesthes,  181. 

Lepidodendroids,  168, 171,  212. 

Lepidodendron,  120,  138,  168,  200;  Stern- 
bergi,  171. 

Lepidoptera,  322. 

Lepidosiren,  156. 

Lepidosteus,  191. 

Lepidostrobus,  170. 

Lepidotus,  283. 

Leptsena,  111,  112,  127,  241;  Liassica, 
242;  sericea,  111. 

Leptocoelia,  129 ;  plano-convexa,  129. 

Lias,  233,  234,  236. 

Lichas,  110. 

Licrophycus  Ottawaensis,  98. 

Ligmtic  Formation  of  North  Amer- 
ica, 298,  304. 

Lily-encrinite,  215,  216. 

Lima,  242. 

Lime,  phosphate  of,  31,  32. 

Limestone,  24-29;  varieties  of,  29-31; 
origin  of,  22;  microscopical  struc- 
ture of,  27;  Crinoidal,  26;  Forma- 


miniferal,  25,  27;  coralline,  26; 
magnesian,  29;  metamorphic,  27; 
oolitic,  30-31;  pisolitic,  30;  bitumi- 
nous, 37;  Laurentian,  67. 

Limnxa,  304;  pyramidalis,  304. 

Limulus,  84,  126,  127,  182. 

Lingula,  88,  89,  111,  129,  149,  202;  Cred- 
neri,  202. 

Lingula  Flags,  78,  79,  89. 

Lingulella,  88;  Davisii,  88;  ferrtir 
ginea,  88. 

Liriodendron,  270,  319;  Meekii,  271. 

Lithostrotion,  176 ;  irregulare,  178. 

Lituites,  132. 

Lizards  (see  Lacertilia). 

Llama,  368. 

Llanberis  Slates,  78. 

Llandeilo  rocks,  93,  95,  97. 

Llandovery  rocks,  94;  Lower,  93;  Up- 
per, 117. 

Lobsters,  183,  215,  240,  275. 

Loess,  352. 

London  Clay,  297,  298. 

Lougmynd  rocks,  77-80,  88. 

Lonsdaleia,  176. 

Lophiodon,  327. 

Lopkophytt'um,  176. 

Lower  Cambrian,  77-79;  Chalk,  266; 
Cretaceous,  264,  265 ;  Devonian,  136; 
Eocene,  297, ">  298;  Greensand,  265, 
266;  Helderberg,  119,  120;  Lauren- 
tian rocks,  66;  Ludlow  rock,  117; 
Miocene,  376;  Old  Red  Sandstone, 
136;  Oolites,  234,  235;  Silurian  per- 
iod, 91-116;  rocks  of,  in  Britain,  93- 
95 ,  in  North  America,  94-97;  life  of, 
98-116. 

Loxonema,  190,  203,  219. 

Ludlow  rocks,  118,  119. 

Lycopodiacese,  120,  139,  170. 

Lynton  Group,  136. 

Lyrodesma,  112. 

Macaques,  334,  343. 

Machxracanthus  major,  154,  157. 

Machairodus,  227,  257,  333,  342,371; 
cultridens,  343. 

Maclurea,  112;  crenulata,  113. 

Macrocheilus,  190,  203,  219. 

Macropetalichthys,  153 ;  Sullivanti,  154. 

Macrotherium  giganteum,  326. 

Macrurous  Crustaceans,  183. 

Mactra,  302. 

Maestricht  Chalk,  267,  288,  295. 

Magnesian  Limestone,  29;  nature 
and  structure  of,  30;  of  the  Per- 
mian series,  198,  200. 

Magnolia,  270,  300,  320. 

Mammalia,  of  the  Trias,  230,  231 ;  of 
the  Jurassic,  261, 262 ;  of  the  Eocene, 
309  314 ;  of  the  Miocene,  324-334 ;  of 
the  Pliocene,  339-343  ;Post-Pliocene, 
361-379. 

Mammoth,  352,  354,  358,  370-372. 

Man,  remains  of,  in  Post-Piiocene 
deposits,  354,357. 

Manatee,  309. 

Mantellia,  237 ;  meqalophylla,  237. 

Maple,  300,  320,  321. 

Marble,  29;  encrinital,  25;  statuary, 
28. 

Marcellus  Shales,  137. 


INDEX. 


423 


Mariacrinus,  125. 

Marmots,  334. 

Marsupials,  809;  of  the  Trias,  230;  of 

the  Jurassic,  261,262 ;  of  the  Eocene, 

309;  of    the   Miocene,    32(5;  of  the 

Post- Pliocene,  361,  362. 
Marsupiocrinuis,  124. 
Marsupites,  274. 
Mastodon,  331,  333,  334;  Americanus, 

angustidenv,   333;    Arvencnsis,    341; 

longirostris,  333;  Ohioticus,  370;  Siva- 

lerutot  332. 

Medina  Sandstone,  118. 
Mcgalichthys,  192. 
Me'galodon,  150. 

Megalomus,  130.  , 

Me'galonyx,  365. 
Mcgalosaurus,  2">6,  287. 
Megatherium,  363,  364;  Cuvieri,  363. 
Melania,  304. 
Melonites,  182. 
Menevian  Group,  77-79. 
Menobranchits,  193. 
Mcristclla  130;  cylindrica,  129;   iwter- 

media,  129;  navijormis,  129. 
Mesopithccus,  334. 
Mesozoic  Period,  45. 
Micheltnia,  145. 
Micraster,  275. 

Microlestes,  230 ;  antiquus,  229. 
Middle  Devonian,  136;  Eocene,  296, 

298,  299;  Oolites,  234 ;  Silurian,  92. 
Miliolite  Limestone,  300. 
3fi»fpo?Y?,237. 
Millstone  Grit,  162,  164. 
Miocene  period,   316;   rocks  of,  in 

Britain,    316;   in    France,  317:   in 

Belgium,  317;  in  Switzerland,  317; 

in  Austria,  317;  in  Germany,  318; 

in  Italy,  318 ;  in  India,  318 ;  in  North 

America,  318;  life  of,  319-334. 
Mitre-shells,  280,  303. 
Mitra,  280,  803. 

Moas  of  New  Zealand,  359-361. 
Modiolopsis,  111 ;  Solvensis,  88. 
Molasse,  317. 
Mole,  334,  349. 
Monkeys,  316,  343, 
Monocotyledonous  plants,  271. 
Monograptus,  101,  121 ;  priodon,  121. 
Monotis,  217. 

Monte  Bolca,  fishes  of,  305. 
Montlivaltia,  215. 
Mosasauroids,  287,  288. 
Mosasaurus,   287 ;   Camperi,  287 ;  prin- 

ceps,  288. 

Mountain  Limestone,  161, 164. 
Mud-fishes,  156,  221. 
Mud-turtles,  289. 
Mull,  Miocene  strata  of,  316. 
Murc.hisonia,  112,  131,  203,  219 ;  gracilis, 

112. 

Murex,  244,  303. 
Muschelkalk.  208,  209,  211. 
Musk-deer,  328. 
Musk-ox,  357,  358,  370. 
Musk-sheep,  370. 
Myliobntis,  Edwardsii,  306. 
Mylodon,  365 ;  robuntus,  365. 
Jfi/ophoria,  216;  Uneata,  216. 
Myriapoda  of  the  Coal,  184,  185. 


Nassa,  303. 

Natatores,  807. 

Natica,  279,  303. 

Nautilus,  113-116,  132,  151,  190,  204,  244, 

280,  304;  Danicus,  280;  pompilius.  244. 
Neanderthal  skull,  378. 
Neocomian  series,  264,  268. 
Neolimulus,  127. 

Nerinxa,  244,  279 ;  Goodhallii.  244. 
Nerita,  303. 
Neuropteria,  322. 
Neuropteris,  138,  167,  200. 
Newer  Pliocene,  335,  336. 
New  Red  Sandstone,  197,  208. 
Newts,  193,  204,  223. 
Niagara  Limestone,  118. 
Nipadites,  300:  ellipticus,  300. 
Nseggerathia,  201. 
Norwich  Crag,  336. 
Nothosaurus,  225 ;  mirabilis,  225. 
Notidanus,  249. 
Numenius  gypKorum,  307. 
Nummulina,  176,    300;  Itevigata;  301; 

pristina,  176. 
Nummulitic  Limestone,  25,  297,  301. 

Oak,  270,  321. 

Obolella,  88 ;  sagittalis,  88. 

Odd-toed  Ungulates,  310,  326,  340,  367. 

Odontaspis,  283. 

Odontopteris,  167 ;   Schlotheimi,  168. 

Odontopteryx,  308;  toliapicus,  308. 

Odontornithes,  290. 

Ogygi'a,  110 ;  Buchii,  108. 

Older  Pliocene,  335,  336. 

Oldhamia,  81;  antiqua.  82;  slates  of 
Ireland,  79,  80. 

Old  Red  Sandstone,  135;  origin  of 
name,  135;  of  Scotland.  136;  rela- 
tions of,  to  Devonian,  135,  136,  157. 

Olenus,  109 ;  micrurus,  88. 

Oligocene,  316. 

Oligoporus,  182. 

Olive-shells,  303. 

Omphyma,  121. 

Onchus,  132;  tenuistriatus,  132. 

Oneida  Conglomerate,  118. 

Onychodus,  156 ;  sigmoides,  154. 

Oolitic  limestone,  structure  of,  80; 
mode  of  formation  of,  30. 

Oolitic  rocks  (see  Jurassic). 

Ooze  Atlantic,  23,  34. 

Ophidia,  260;  of  the  Eocene,  306. 

Ophiuridea,  of  the  Lower  Silurian, 
106 ;  of  the  Upper  Silurian,  122;  of 
the  Carboniferous,  180;  of  the 
Trias,  215 ;  of  the  Jurassic,  246. 

Opossum,  309,  326. 

Orbitoides,  301. 

Oriskany  Sandstone,  137. 

Ormoxylon,  140. 

Orohippus,  312. 

Orthis,  89,  111,  127,  149,  188,  111;  bifor- 
ata,  110 ;  Davidsoni,  129 ;  elegantula, 
129;  flabellulum,  110;  Hicksii,  88; 
lenticularis,  88;  plicatella,  111:  re- 
supinata,l89 ;  subquadrata,  110 ;  tes^w- 
dinaria,  111. 

Orthoceras  89, 114,  115, 132, 151,  190, 114 ; 
crebriseptnm,  114. 

Orthonota,  112. 

Orthoptera,  185,  322. 


424 


INDEX. 


Osmeroides,  284  ;  MantcUi,  284. 

Osmerus,  285. 

Osteolepis,  156. 

Ostracode,  Crustaceans  of  the  Cam- 
brian, 84;  of  the  Lower  Silurian, 
109;  of  the  Upper  Silurian,  125;  of 
the  Devonian,  146;  of  the  Carboni- 
ferous, 183;  of  the  Permian,  202;  of 
the  Trias,  215;  of  the  Jurassic,  240; 
of  the  Cretaceous,  275. 

Ostrea  acuminata,  242;  Couloni,  111; 
deltoidea,  242  ;  distorta,  242  ;  expansa, 
gregarea,  242  ;  Marshii,  242,  243. 

Otodus,  305  ;  obliquus,  306. 

Otozamites,  234. 

Otozoum,  211. 

Oudenodon,  226  ;  Bainii,  227. 

Ovibos  moschatus,  370. 

Oxford  Clay,  234,  236. 

Oxyrhina,  323  ;  xiphodon,  324. 

Oysters,  242,  243,  277. 

Pachyphyllum,  176. 

Palxarca,  112. 

Palxaster,  123;  Kuthveni,  123. 

Palasterina,  122  ;  primceva,  123. 

Palxchinus,  122,  182  ;  elliptic™,  181. 

Palxocaris,  184,  ft/pws,  184. 

Palxocoma,  122  ;  Colvini,  123. 

Palxocoryne,  176. 

Palxolithic  man,  remains  of,  377-379. 

Palxomanon,  120. 

Palxoniscus,  192,  204. 

Palxontina  Oolitica,  241. 

Palseontological  evidence  as  to  Evo- 

lution, 61,  386-388. 
Palaeontological    record,    imperfec- 

tion of  the,  51,  52. 
Palaeontology,  definition  of,  10. 
Palxonyctis,  315. 
Palseophis,    306:   toliapicus,    306;    <y- 


Palxoreas,  329. 

Palxosaurus,  206,  225;  platyodon,  225. 

Palxosiren  Beinerti,  204. 

Palseotherium,  3  0  ;  magnum,  311. 

Palxoxylon,  173. 

Palaeozoic  period,  45. 

Palms,  237,  271,  300,  319,  320. 

Paludina,  267,  304. 

Pandaneoe,  237. 

Pandanus,  270. 

Paradoxides,  86,  87,  109;  Bohemicus,  86. 

Parasmilia,  274. 

Parkeria,  272. 

Pear  Encrinite,  238. 

Pearly  Nautilus,  58,  112,  113,  244. 

Peccaries,  328. 

Pecopteris,  138,  167,  200. 

Pecten  Grcenlandicus,  351;  Islandicus, 

351  ;  Valoniensis,  216,  217,  209. 
Penarth  Beds,  209. 
Pennatulidx,  302. 
Pentacrinus,  238;    caput-medusse,  238; 

fasciculosus,  239. 
Pentamerus,    128,    128;   galeatus,  129; 

Knightii,  130. 

Pentremites,  (see  Blastoidea). 
Pentremites  conoidcus,  180  ;  pyriformis, 

180. 

Perching  Birds,  307. 
Percida,  284. 


Periechocrinus,  125. 

Perissodactyle  Ungulates,  310,  326,339. 

Permian  period,  196-207;  rocks  of,  in 
Britain,  198;  in  North  America, 
199;  life  of,  200-312. 

Persistent  types  of  life,  59,  386. 

Petalodus.  192. 

Piaster,  122. 

Petroleum,  origin  of,  37. 

Pezophaps,  361. 

Phacops,  110,  126,  146;  Doumingice,  126; 
granulatus,  147;  tevis,  147 ;  latifrons, 
147, 146  ;  longicaudatm,  126 ;  rana,  146. 

Phcenopora  ertsiformis,  128. 

Phalangers.362. 

Phanerogams,  167. 

Phaneropleuron,  156. 

Phascolotherium,  261,  261. 

Pheronema,  272. 

Phillipsastrsea,  144. 

Phillipsia,    183;  seminifera,  184. 

Pholadomya,  242. 

Phormosoma,  181. 

Phorus,  279. 

Phosphate  of  lime,  concretions  of, 
31;  disseminated  in  rocks,  31;  ori- 
gin of,  32. 

Phyllograptus,  104 ;  ft/pits,  103. 

Phyllopoda,  of  the  Cambrian,  84;  of 
the  Lower  Silurian,  109;  of  the  Up- 
per Silurian,  125;  of  the  Devonian, 
148;  of  the  Carboniferous,  183;  of 
the  Permian,  201 ;  of  the  Trias,  216. 

Phylloporn,  216. 

Physa,  304 ;  columnaris,  304. 

Pigs,  313, 328, 340,  367. 

Pilton  Group,  136. 

Pinites,  173. 

Pisces  (see  Fishes). 

Pisolite,  30. 

Pisolitic  Limestone  of  France,  265, 
295. 

Placodus,  226 ;  fi^os,  226. 

Placoid  Fishes,  152;  of  the  Upper 
Silurian,  132,  133;  of  the  Devonian, 
155-156;  of  the  Carboniferous.  191; 
of  the  Permian,  204;  of  the  Trias, 
220;  of  the  Jurassic,  249;  of  the 
Cretaceous,  283;  of  the  Eocene,  305 ; 
of  the  Miocene,  323. 

Plagiaulax,  261. 

Planolites,  125;  vulgaris,  125. 

Planorbis,  304. 

Plants,  of  the  Cambrian,  80,  81;  of 
Lower  Silurian,  98,  99;  of  the  Up- 
per Silurian,  120;  of  the  Devonian, 
138-141 ;  of  the  Carboniferous,  167- 
174;  of  the  Permian,  200;  of  the 
Trias,  212,  213;  of  the  Jurassic,  236, 
237;  of  the  Cretaceous,  269,  271;  of 
the  Eocene, 299, 300;  of  the  Miocene, 
319-322. 

Plasmopora,  121. 

Platanus,  270,  320 ;  aceroides,  320. 

Platephemera  antiqua,  147. 

Platiiceras,  130,  151;  dumosum,  151; 
multisinuatum,  131;  ventricosum,  131. 

Plaiycrinus,  124,  178;  tricontadactylus, 
179 

Platyostoma,  131;  Niagarense,  131. 

Platyrhine  Monkeys,  375. 

Platyschisma  helicites,  131. 


INDEX. 


425 


Platysomus,  204  ;  gibbosus,  203. 

Platystoma,  219. 

Pleistocene  period,  346;  climate  of , 
375. 

Plesiosaurus,  225,  251-255,  285 ;  ctoMcto- 
deirus,  251. 

Pleurocystites  squamosus,  107. 

Pleurotoma,  303. 

Pleurotomaria,  112, 131, 190, 203,  244, 279. 

Plicatula,  219. 

Pliocene  period,  335;  rocks  of,  in 
Britain,  336;  in  Belgium.  337;  in 
Italy,  337;  in  North  America,  337; 
life  of,  338-343. 

Pliopithecus.  334;  antiques,  334. 

Pliosaurus,  252. 

Podocarya,  237 . 

Podozamites,  213;  lanceolalus,  214. 

Polir-schiefer,  34. 

Polycystina,  34;  of  Barbadoes-earth, 
34. 

Polypora,  148, 186 ;  dendroides,  187. 

Polypterus,  155,  191. 

Polystvmella,  322. 

Polytremacis,  274. 

Polyzoa,  of  the  Cambrian,  82,  90;  of 
the  Lower  Silurian,  110;  of  the 
Upper  Silurian,  127;  of  the  De- 
vonian. 147, 148;  of  the  Carbonifer- 
ous,186',  187 ;  of  the  Permian,  202 ;  of 
the  Trias,  215;  of  the  Cretaceous, 
275 ;  of  the  Miocene,  323. 

Populus,  272. 

Porcellia,  190. 

Porcupines,  333. 

Portage  Group,  137. 

Port-Jackson  Shark,  156, 192,249. 

Portland  beds,  234,  236. 

Post-Glacial  deposits,  348,  351. 

Post-Pliocene  period,  346. 

Post-Tertiary  period,  296. 

Poteriocrinus,  179 

Potsdam  Sandstone,  79. 

Pre-Glacial  deposits,  848. 

Prestwichia,  182 ;  rotundata,  183. 

Primitia,\09 ;  strangulata,  108. 

Primordial  Trilobites,  85. 

Primordial  zone,  79. 

Proboscidea,  of  the  Miocene,  331,  334 ; 
of  the  Pliocene,  341,  342;  of  the 
Post-Pliocene,  370.  373. 

Producta,  150,  188,  202;  horrida,  202; 
longispina,  189;  semireticulata,  189. 

Productella,  150,  188. 

Productidse,  149,  216. 

Proetus,  126. 

Prong-buck,  330. 

Protaster,  122 ;  Sedgwickii,  123. 

Proteaceas,  270,  320. 

Proteus,  193 

Protichni'es,  87. 

Protocystites,  82. 

Protornis  Glarisiensis,  307. 

Protorosaurus,  2  6 ;  Speneri,  205. 

Protospongia,  82 ;  fenestrata,  88. 

Prototaxites,  120, 140;  Logani,  141. 

Psammobia,  302. 

Psammodus,  192. 

Psaronius,   138, 167. 

Pseudocrinus  bifasciatus,  107. 

Psilophyton,  120, 189,  140;  princeps.  140. 

Pteranodon,  254,  285;  longiceps,  285. 


Pteraspis,  132, 154 ;  Banksii,  132. 
Plerichthys,  154 ;  cor  nut  as,  i56. 
Pterincea,  130 ;  subfa/cata,  130. 
Pteroceras,  244,  280. 

Pterodactylus,  252,  265 ;  crassirostris,  253. 
Pternphyllum.  213,  237 ;  Jcegeri,  214. 
Pteropoda,  of  the  Cambrian,  89 ;  of  the 

Lower  Silurian,  112;  of  the  Upper 

Silurian,  131 ;  of  the  Devonian,  151 ; 

of  the  Carboniferous,  189;  of  the 

Permian,  2'>3;  of  the  Jurassic,  244. 
Pterosauria,  252;  of  the  Jurassic,  252- 

255;  of  the  Cretaceous,  285. 
Pterygotus  Anglicus,  126, 127. 
Ptilodictya,  110,  127;  acwta.  109;/aZa'- 

/orww's  109;  raripora,    128;  Schafferi, 

109. 

Ptychoceras,  281 ;  Ewericianum,  282. 
Ptychodus,  283. 
Pupa  vetueta,  190. 

Purbeck  Beds,  234;  Mammals  of,  262. 
Purpuroidea,  244. 
Pycnodus,  283. 
Pyrula,  303. 

Quadrumana,  of  the  Eocene,  316;  of 
the  Miocene,  334;  of  the  Plio- 
cene, 343 :  of  the  Post- Pliocene,  375. 

Quadrupeds  (see  Mammalia). 

Quaternary  period,  346. 

Quebec  Group,  96, 97, 101. 

Qutrcus,  270. 

Rabbits,  333. 

JZana,  324. 

Raptores,  308. 

Rasores.  307. 

Recent  period,  296,  346. 

Receptaculites,  99. 

Red  clays,  origin  of,  36. 

Red  Coral,  322. 

Red  Crag,  335. 

Red  Deer,  349,  368. 

Reindeer,  367,  358,  368,  369. 

Remopleurides,  120. 

Reptiles,  204;  of  the  Permian,  204- 
2u7;  of  the  Trias,  223-227;  of  the 
Jurassic,  249-258;  of  the  Cretace- 
ous, 285-290;  of  the  Eocene,  306, 307. 

Retepora,  110,  127,  148,  186,  202,  216; 
Ehrenbergi,  202 ;  Phittipsi,  148. 

Retiolites,  121. 

Retzia,  130. 

Rhaetic  Beds,  209-211. 

Phamphorhynchus,  255 ;  Bucklandi,  255. 

Rhinoceridse,  326. 

Rhinoceros  Etruscus,  339,340,  349,  367; 
leptorhinus,  339 ;  megarhinus,  339-340, 
349,  367 ;  tichorhinus,  367. 

Rhinopora  verrucoaa,  128. 

Rhizodus,  192. 

Rhombus  minimus,  305. 

Rhyncholites,  246. 

RhynchoneUa,  112, 130, 149, 188,  241 ,  276, 
302 ;  cuneata,  129 ;  neplecta,  129 ;  pfe«- 
rodon,  189;  varians,  242. 

Rhi/nchosaurus,  224;  articeps,  224. 

Rice-shells,  303. 

Richmond  Earth,  35,  818. 

Ringed  Worms  (see  Annelida). 

River-gravels,  high-level  and  low- 
level,  352-353. 


426 


INDEX. 


Robulina,  322. 

Rocks,  definition  of,  15;  divisions  of, 
15,  16;  igneous,  15;  aqueous,  17-19; 
mechanically-formed,  19-21 ;  chem- 
ically -  formed,  21 ;  organically- 
formed, 21-38;  arenaceous,  21;  argil- 
laceous, 21;  calcareous.  21-33;  sili- 
ceous, 21,33-35. 

Rodentia  of  the  Eocene,  316;  of  the 
Miocene,  333;  of  the  Post-Pliocene, 
375. 

Roebuck.  349,  368. 

Hostellana,  214,  303. 

Jtotalia,  23,  99,  175,  272;  Boueana,  272. 

Rugose  Corals,  105;  of  the  Lower 
Silurian,  106;  of  the  Upper  Sil- 
urian, 121;  of  the  Devonian,  144; 
of  the  Carboniferous,  176-177 ;  of  the 
Permian,  251;  of  the  Upper  Green- 
sand,  274. 

Rupelian  Clay,  318. 


Sabal  major,  319. 
Sabre-toothed  Tiger,  333,  343. 
Saccammina,  175. 
Saccosoma,  239. 
Salamanders,  193,  324. 
Salina,  Group,  119. 


Salmonidce,  284. 

Sao  hirsuta,  85. 

Sassafras  cretacea,  271. 

Sauropterygia,  225. 

Scalaria,  279,  303  ;  Orcelandica,  351. 

Scaphites,  281,  282;  cequalis,  282. 

Schizodus,  203,  217. 

Schoharie  Grit,  137,  139. 

Scolecoderma,  83. 

Scoliostoma,  219. 

Scolithus,  83  ;  Canadensis,  108. 

Scorpions  of  the  Coal-measures,  185. 

Scorpion-shells,  280. 

Screw-pines,  237. 

Scutetta,  822  ;  subrotunda,  323. 

Sea-cows  (see  Sirenia). 

Sea-lilies  (see  Crinoidea). 

Sea-lizards  (see  Enaliosaurians). 

Seals,  333. 

Sea-mats  and  Sea-mosses  (see  Poly- 

zoa). 

Sea-shrubs  (see  Gorgonidse). 
Sea-urchins  (see  Echinoidea). 
Sea-weeds,  80,  81,  84,  98,  138,  167,  269. 
Secondary  period,  45. 
Sedimentary  rocks,  15. 
Semnopithecus,  334,  343. 
Septaria,  32. 
Sequoia,  316,320  ;  Couttfix,  320  ;  gigantea, 

320;  Langsdorffi,3'2Q. 
Scrolls,  84. 

Serpents  (see  Ophidia). 
Serpulites,  125. 

Sewalik  Hills  (see  SiwAlik  Hills). 
Sheep,  369. 
Shell-sands,  20. 
SigUlaria,  170,  172;  Orceseri,  172. 
Sigillarioids.  138,  .70,  173,200. 
Silicates,  in  filtration  of  the  shells 

of  Foraminifera  by,  35,  74. 
Siliceous  rocks,  21,  33. 
Siliceous  Sponges,  273. 


Silicification,  13, 14. 

Silurian  period  (see  Lower  Silurian 
and  Upper  Silurian), 91-116, 117-134. 

Simosaurus,  224 ;  (.laillardoti,  224. 

Siphonia,  272;ficw>,  273. 

Siphonostomatous  Univalves,  241, 
280,  303. 

Siphonotreta,  112. 

Sirenia,  309, 331 ;  of  the  Eocene,  309 ;  of 
the  Miocene,  326. 

Siren  lacertina,  204. 

Sivatherium,  329 ;  giganteum,  329. 

Siwalik  Hills,  Miocene  strata  of,  318. 

Skiddaw  Slates,  102. 

Sloths,  326,  363,  364. 

Smilax,  320. 

Smithia,  176. 

Snakes  (see  Ophidia). 

Soft  Tortoises, 306. 

Solarium,  279. 

Solenhofen  Slates,  235. 

Solitaire,  359,  361. 

Spalacotfierium,  262. 

Spatangus,  322. 

Sphcerospongia,  141. 

Sphagodus,  132. 

Sphenodon,  224. 

Sphenopteris,  138, 167,  200. 

Spiders  of  the  Coal-measures,  185. 

Spider-shells,  244. 

Spindle-shells,  244. 

Spirifera,I28, 149, 188,  202,  241;  crispa, 
129;  disjuncta,  149;  hysterica,  128; 
mucronata,  149 ;  Niagarensis,  1 29 ;  ros- 
trata,  242 ;  sculptilis,  149 ;  trigoncUis, 
189. 

Spiriferidse,  149. 

Spirophyton  cauda-Oatti,  137,  167. 

Spirorbis,  125, 145, 182;  Arkonensis,  146; 
Carbonarius,  182;  laxus,  146;  Lewisii. 
12- ;  omphalodes,  146;  swrmfyfero,  146. 

Spirulirostra,  323. 

Spondylus,  277 ;  spinosus,  278. 

Sponges,  of  the  Cambrian,  82 ;  of  the 
Lower  Silurian,  99 ;  of  the  Upper 
Silurian,  120;  of  the  Devonian, 
141;  of  the  Carboniferous,  175;  of 
the  Permian,  201 ;  of  the  Trias,  214; 
of  the  Jurassic,  237;  of  the  Cre- 
taceous, 272,  273. 

Spongilla,  201. 

Spongillopsis,  201. 

Spongophyllum,  176. 

Spore-cases,  of  Cryptogams  in  the 
Ludlow  rocks,  120;  in  the  Coal,  165. 

Squirrels,  334. 

Stagonolepis,  224. 

Staircase-shells,  279. 

Stalactite,  22. 

Stalagmite,  22. 

Star-corals,  238. 

Star-fishes,  106, 122.  216. 

St.  Cassian  Beds.  209,  210. 

Stephanophyllia,  274. 

Stereognathus,  261,  262. 

Stigmaria.  173;flcoides,  173. 

Stouesfield  Slate,  234;  Mammals  of, 
261. 

Strata,  contemporaneity  of,  45. 

Stratified  rocks,  16-19. 

Streptelasma,  106. 

Streptorhynchus,  202. 


INDEX. 


427 


Stroinntopora,  99,100, 120, 141;  rugosa,  99; 

(uberculata,  142. 
Stroiubodes,  121;  pentagonus,  105. 

trombus,  280. 
Strophalosia,  202. 
Mrophodus,  262. 
Strophomena,  IIP,  111,  127, 149,  188 ;  o#er- 

nato,  111;  ddtoidea,  110;  filitexta,   111; 

rhomboidalis,  150,  }5'2\subplana,  129. 
Sub-Appennine  Beds,  337. 
Sub-Carboniferous  rocks,  161,  164. 
Succession  of  life  upon  the  globe, 

381-388. 

S-uda,  313,  328.  340. 
Sulphate  of  lime,  23. 
Sus  Erymanthius,  328;  scrofa,  367. 
Synastrcsa,  215. 
Synhelia  Sharpeana,  274. 
Synocladia,  202;  virgulacea,  202. 
Syringopora,  121,  1/4;  ramulosa,  178. 

Tabulate  Corals,  106;  of  the  Lower 
Silurian,  106;  of  the  Upper  Silu- 
rian, 121;  of  the  Devonian,  141;  of 
the  Carboniferous,  176;  of  the  Per- 
mian, 201. 

Talpa  Europvea,  349. 

Tapiridx,  310. 

Tapirs,  310. 

Tapirus  Arvernensis,  3 10. 

Taxocrimis  tuber culatus,  124. 

Taxodium,  270,  319,  321. 

Teleosaurus,  260. 

Teleostean  Fishes,  152;  of  the  Cre- 
taceous, 283. 

Telerpeton  Elginense,  224. 

Tettina  proximo,  351. 

Tentaculites,  131,  151;  ornatus,  131. 

Terebra,  303. 

Terebratella,  276;  Astieriana,  276. 

Terebratula,  188,  241;  digona,  242:  efon- 
#ota,  202;  hastata  186;  quadrifida,  242; 
sphoRroidalis,  '242. 

Terebratulina,  276;  caput-serpentis,  276; 
sonata,  276. 

Termites,  322. 

Terrapins,  289,  306. 

Tertiary  period,  45,  294-296. 

Tertiary  rocks,  classification  of,  295- 
296. 

Testudinidx,  324. 

Tetrabranchiate  Cephalopoda,  114; 
of  the  Cambrian,  89;  of  the  Lower 
Silurian.  113-116;  of  the  Upper  Silu- 
rian, 132;  of  the  Devonian,  151 ;  of 
the  Carboniferous,  189,  190;  of  the 
Permian,  203;  of  the  Trias,  217;  of 
the  Jurassic,  244,  246;  of  the  Cre- 
taceous, 280-283;  of  the  Eocene, 
304;  of  the  Miocene,  322. 

Textularia,  23,  272,  322;  Meyeriana,   322. 

Thanet  Sands  297,  298. 

TVca,  89.  112,131. 

Theca  Damdii,  88. 

Thecidium,  219. 

Thecodont  Reptiles,  224. 

Thecodontosaurus,  206,  224;  antiquus, 
225. 

Thecosmilia  annulai  is,  238. 

Thelodus,  132. 

Theriodont  Reptiles,  206,  227. 

Thylacoleo,  362. 


Tile-stones,  118. 

Titanotherium,  327. 

Toothed  Birds,  289-292. 

Tortoises,  207,  306. 

Tragoceras,  329. 

Travertine,  22, 

Tree-Ferns,  of  the  Devonian,  138;  of 
the  Coal-measures,  169. 

Tremadoc  Slates,  78-79. 

Trematis,  112. 

Trenton  Limestone,  96,  97. 

Triarthrus  Beckii,  108. 

Triassic  period,  209;  rocks  of,  in 
Britain,  209;  in  Germany.  209;  in 
the  Austrian  Alps,  210;  in  North 
America,  210;  life  of,  211-231. 

Triconodon,  262. 

Trigonia,  24  ',  262,  277. 

Trigoniadif,  203,  217. 

Trigonocarpum,  173 ;  ovatum,  173. 

Trilobites,  H4-88;  of  the  Cambrian, 
86,88;  of  the  Lower  Silurian,  108, 
109;  of  the  Upper  Silurian.  125,  126; 
of  the  Devonian.  146,147;  of  the 
Carboniferous,  183. 

Trimerellidse,  129. 

Trinucleus,  110 ;  concentricus,  108. 

Trionycidse,  306. 

Triton,  803. 

Trochocyathus,  274. 

Trochonema,  131. 

Trogontherium,  375 ;  Cuvieri,  349,  375. 

Trumpet-shells,  303. 

Tulip-tree,  270,  319. 

Turbinolia  sulcata,  302. 

Turbinolidx,  302. 

Turrilites,  281,  282 ;  catenulatus,  281. 

Turritella,  279,  303. 

Turtles,  207,  259,  281,  306. 

Typhis  tubifer,  803. 

UUmania  selaginoides,  201. 

Unconformability  of  strata,  50. 

Under-clay  of  coal,  165. 

Ungulata,  of  the  Eocene,  310-313:  of 
the  Miocene,  326-330;  of  the  Plio- 
cene, 339-340 ;  of  the  Post- Pliocene, 
366-367. 

Uniformity,  doctrine  of,  5-7. 

Unio,  277. 

Univalves  (see  Gasteropoda). 

Upper  Cambrian,  77-79;  Chalk,  266; 
Cretaceous,  264.  268;  Devonian,  137; 
Eocene,  296,  298;  Greensand,  2ftO; 
Helderberg,  1*7;  Laurentian,  66; 
Llandovery,  117;  Ludlow  rock,  117; 
Miocene,  316;  Oolites,  234;  Silurian 
period,  116;  rocks  of,  in  Britain, 
117,  118;  in  North  America,  118-120, 
life  of,  120-134. 

Ursus  arctos,  373;  Arvernensis,  341;  fe- 
rox,  373;  speloea,  3'<3. 

Ursus,  349,  369. 

\  ailey-  gravels,  high-level  and  iow- 

level,  352-354. 
Vanessa  Pluso,  322. 
Varanidtz,  206. 
Vegetation  (see  Plants). 
Vcntriculites,  272,  273:  simplex,  273. 
Venus's  Flower-basket,  273. 
Vermilia,  201. 


428 


INDEX. 


Vespertilio  Paris  iensis,  315. 
Vicksburg  Beds,  299. 
Vines,  316,  320,  321. 
Vitreous  Sponges,  272. 
Vottzia,  213;  heterophylla,  214. 
Valuta,  279,  303;  elongata,  279. 
Volutes,  280,  303,  323. 

IValchia,  200,  201;  piniformis,  200. 

Walrus,  333. 

Wealden  Beds,  264. 

Wellingtonia,  320. 

Wenlock  Beds,  117,  119;   Limestone, 

117 ;  Shale,  117. 
Wentle-traps,  279. 
Werfen  Beds,  210,  211. 
Whalebone  Whales,  309,  326. 
Whales,  309,  326. 
Whelks,  244. 
White  Chalk,  266 ;  structure  of,  22,  23 : 

origin  of,  24,  271. 
White  Crag,  335. 
White  River  Beds,  318. 
Wild  Boar,  367. 


Williamsonia,  237. 

Winged  Lizards  (see  Pterosauria), 

Winged  Snails  (ra;  Pteropoda).    ' 

Wing-shells,  280. 

Wolf,  349,  374. 

Wolverine,  374. 

Wombats,  362. 

Woolhope  Limestone,  117. 

Woolly  Rhinoceros,  352,  354,  357,  367. 

Woolwich  and  Reading  Beds,  298. 

Worm-burrows,  83,  84,  123. 

Xanthidia,  141. 
Xenoneura  antiquorum,  147. 
Xiphondon,  313. 
Xylobius,  186 ;  Sigillarise,  186. 

Zamia  spiralis,  213. 

Zamiies,  213,  237,  321. 

Zaphrentis,  106,  r.  1,  144,  177;  cornicula, 

143;  Stokesi,  105 ;  vermicularis,  178. 
Zeacrinus,  179. 
Zechstein,  198. 
Zeuglodon,  309,  326;  cetoides,  310. 


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